a105877646
The idea behind this canonicalization is that it allows us to handle less patterns, because we know that some will be canonicalized away. This is indeed very useful to e.g. know that constants are always on the right. However, this is only useful if the canonicalization is actually reliable. This is the case for constants, but not for arguments: Moving these to the right makes it look like the "more complex" expression is guaranteed to be on the left, but this is not actually the case in practice. It fails as soon as you replace the argument with another instruction. The end result is that it looks like things correctly work in tests, while they actually don't. We use the "thwart complexity-based canonicalization" trick to handle this in tests, but it's often a challenge for new contributors to get this right, and based on the regressions this PR originally exposed, we clearly don't get this right in many cases. For this reason, I think that it's better to remove this complexity canonicalization. It will make it much easier to write tests for commuted cases and make sure that they are handled.
318 lines
9.4 KiB
LLVM
318 lines
9.4 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -passes=instcombine -S | FileCheck %s
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; If we have a masked merge, in the form of: (M is not constant)
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; ((x ^ y) & ~M) ^ y
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; We can de-invert the M:
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; ((x ^ y) & M) ^ x
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define i4 @scalar (i4 %x, i4 %y, i4 %m) {
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; CHECK-LABEL: @scalar(
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: [[TMP1:%.*]] = and i4 [[N0]], [[M:%.*]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[TMP1]], [[X]]
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; CHECK-NEXT: ret i4 [[R]]
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;
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%im = xor i4 %m, -1
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%n0 = xor i4 %x, %y
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%n1 = and i4 %n0, %im
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%r = xor i4 %n1, %y
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ret i4 %r
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}
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; ============================================================================ ;
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; Various cases with %x and/or %y being a constant
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; ============================================================================ ;
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define i4 @in_constant_varx_mone_invmask(i4 %x, i4 %mask) {
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; CHECK-LABEL: @in_constant_varx_mone_invmask(
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; CHECK-NEXT: [[N1_DEMORGAN:%.*]] = or i4 [[X:%.*]], [[MASK:%.*]]
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; CHECK-NEXT: ret i4 [[N1_DEMORGAN]]
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;
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%notmask = xor i4 %mask, -1
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%n0 = xor i4 %x, -1 ; %x
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%n1 = and i4 %n0, %notmask
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%r = xor i4 %n1, -1
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ret i4 %r
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}
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define i4 @in_constant_varx_6_invmask(i4 %x, i4 %mask) {
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; CHECK-LABEL: @in_constant_varx_6_invmask(
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[X:%.*]], 6
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; CHECK-NEXT: [[TMP1:%.*]] = and i4 [[N0]], [[MASK:%.*]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[TMP1]], [[X]]
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; CHECK-NEXT: ret i4 [[R]]
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;
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%notmask = xor i4 %mask, -1
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%n0 = xor i4 %x, 6 ; %x
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%n1 = and i4 %n0, %notmask
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%r = xor i4 %n1, 6
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ret i4 %r
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}
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define i4 @in_constant_mone_vary_invmask(i4 %y, i4 %mask) {
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; CHECK-LABEL: @in_constant_mone_vary_invmask(
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; CHECK-NEXT: [[MASK_NOT:%.*]] = xor i4 [[MASK:%.*]], -1
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; CHECK-NEXT: [[R:%.*]] = or i4 [[Y:%.*]], [[MASK_NOT]]
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; CHECK-NEXT: ret i4 [[R]]
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;
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%notmask = xor i4 %mask, -1
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%n0 = xor i4 -1, %y ; %x
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%n1 = and i4 %n0, %notmask
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%r = xor i4 %n1, %y
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ret i4 %r
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}
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define i4 @in_constant_6_vary_invmask(i4 %y, i4 %mask) {
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; CHECK-LABEL: @in_constant_6_vary_invmask(
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[Y:%.*]], 6
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; CHECK-NEXT: [[TMP1:%.*]] = and i4 [[N0]], [[MASK:%.*]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[TMP1]], 6
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; CHECK-NEXT: ret i4 [[R]]
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;
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%notmask = xor i4 %mask, -1
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%n0 = xor i4 %y, 6 ; %x
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%n1 = and i4 %n0, %notmask
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%r = xor i4 %n1, %y
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ret i4 %r
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}
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; ============================================================================ ;
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; Commutativity
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; ============================================================================ ;
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; Used to make sure that the IR complexity sorting does not interfere.
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declare i4 @gen4()
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; FIXME: should the %n1 = and i4 %im, %n0 swapped order pattern be tested?
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define i4 @c_1_0_0 (i4 %x, i4 %y, i4 %m) {
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; CHECK-LABEL: @c_1_0_0(
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[Y:%.*]], [[X:%.*]]
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; CHECK-NEXT: [[TMP1:%.*]] = and i4 [[N0]], [[M:%.*]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[TMP1]], [[X]]
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; CHECK-NEXT: ret i4 [[R]]
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;
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%im = xor i4 %m, -1
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%n0 = xor i4 %y, %x ; swapped order
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%n1 = and i4 %n0, %im
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%r = xor i4 %n1, %y
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ret i4 %r
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}
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define i4 @c_0_1_0 (i4 %x, i4 %y, i4 %m) {
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; CHECK-LABEL: @c_0_1_0(
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: [[TMP1:%.*]] = and i4 [[N0]], [[M:%.*]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[TMP1]], [[Y]]
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; CHECK-NEXT: ret i4 [[R]]
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;
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%im = xor i4 %m, -1
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%n0 = xor i4 %x, %y
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%n1 = and i4 %n0, %im
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%r = xor i4 %n1, %x ; %x instead of %y
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ret i4 %r
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}
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define i4 @c_0_0_1 (i4 %m) {
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; CHECK-LABEL: @c_0_0_1(
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; CHECK-NEXT: [[X:%.*]] = call i4 @gen4()
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; CHECK-NEXT: [[Y:%.*]] = call i4 @gen4()
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[X]], [[Y]]
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; CHECK-NEXT: [[TMP1:%.*]] = and i4 [[N0]], [[M:%.*]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[TMP1]], [[X]]
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; CHECK-NEXT: ret i4 [[R]]
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;
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%im = xor i4 %m, -1
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%x = call i4 @gen4()
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%y = call i4 @gen4()
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%n0 = xor i4 %x, %y
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%n1 = and i4 %n0, %im
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%r = xor i4 %y, %n1 ; swapped order
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ret i4 %r
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}
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define i4 @c_1_1_0 (i4 %x, i4 %y, i4 %m) {
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; CHECK-LABEL: @c_1_1_0(
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[Y:%.*]], [[X:%.*]]
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; CHECK-NEXT: [[TMP1:%.*]] = and i4 [[N0]], [[M:%.*]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[TMP1]], [[Y]]
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; CHECK-NEXT: ret i4 [[R]]
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;
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%im = xor i4 %m, -1
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%n0 = xor i4 %y, %x ; swapped order
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%n1 = and i4 %n0, %im
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%r = xor i4 %n1, %x ; %x instead of %y
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ret i4 %r
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}
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define i4 @c_1_0_1 (i4 %x, i4 %m) {
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; CHECK-LABEL: @c_1_0_1(
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; CHECK-NEXT: [[Y:%.*]] = call i4 @gen4()
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[Y]], [[X:%.*]]
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; CHECK-NEXT: [[TMP1:%.*]] = and i4 [[N0]], [[M:%.*]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[TMP1]], [[X]]
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; CHECK-NEXT: ret i4 [[R]]
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;
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%im = xor i4 %m, -1
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%y = call i4 @gen4()
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%n0 = xor i4 %y, %x ; swapped order
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%n1 = and i4 %n0, %im
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%r = xor i4 %y, %n1 ; swapped order
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ret i4 %r
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}
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define i4 @c_0_1_1 (i4 %y, i4 %m) {
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; CHECK-LABEL: @c_0_1_1(
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; CHECK-NEXT: [[X:%.*]] = call i4 @gen4()
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[X]], [[Y:%.*]]
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; CHECK-NEXT: [[TMP1:%.*]] = and i4 [[N0]], [[M:%.*]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[TMP1]], [[Y]]
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; CHECK-NEXT: ret i4 [[R]]
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;
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%im = xor i4 %m, -1
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%x = call i4 @gen4()
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%n0 = xor i4 %x, %y
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%n1 = and i4 %n0, %im
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%r = xor i4 %x, %n1 ; swapped order, %x instead of %y
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ret i4 %r
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}
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define i4 @c_1_1_1 (i4 %m) {
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; CHECK-LABEL: @c_1_1_1(
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; CHECK-NEXT: [[X:%.*]] = call i4 @gen4()
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; CHECK-NEXT: [[Y:%.*]] = call i4 @gen4()
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[Y]], [[X]]
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; CHECK-NEXT: [[TMP1:%.*]] = and i4 [[N0]], [[M:%.*]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[TMP1]], [[Y]]
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; CHECK-NEXT: ret i4 [[R]]
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;
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%im = xor i4 %m, -1
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%x = call i4 @gen4()
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%y = call i4 @gen4()
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%n0 = xor i4 %y, %x ; swapped order
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%n1 = and i4 %n0, %im
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%r = xor i4 %x, %n1 ; swapped order, %x instead of %y
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ret i4 %r
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}
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define i4 @commutativity_constant_varx_6_invmask(i4 %x, i4 %mask) {
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; CHECK-LABEL: @commutativity_constant_varx_6_invmask(
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[X:%.*]], 6
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; CHECK-NEXT: [[TMP1:%.*]] = and i4 [[N0]], [[MASK:%.*]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[TMP1]], [[X]]
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; CHECK-NEXT: ret i4 [[R]]
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;
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%notmask = xor i4 %mask, -1
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%n0 = xor i4 %x, 6 ; %x
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%n1 = and i4 %notmask, %n0 ; swapped
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%r = xor i4 %n1, 6
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ret i4 %r
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}
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define i4 @commutativity_constant_6_vary_invmask(i4 %y, i4 %mask) {
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; CHECK-LABEL: @commutativity_constant_6_vary_invmask(
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[Y:%.*]], 6
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; CHECK-NEXT: [[TMP1:%.*]] = and i4 [[N0]], [[MASK:%.*]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[TMP1]], 6
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; CHECK-NEXT: ret i4 [[R]]
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;
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%notmask = xor i4 %mask, -1
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%n0 = xor i4 %y, 6 ; %x
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%n1 = and i4 %notmask, %n0 ; swapped
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%r = xor i4 %n1, %y
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ret i4 %r
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}
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; ============================================================================ ;
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; Negative tests. Should not be folded.
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; ============================================================================ ;
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; One use only.
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declare void @use4(i4)
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define i4 @n_oneuse_D_is_ok (i4 %x, i4 %y, i4 %m) {
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; CHECK-LABEL: @n_oneuse_D_is_ok(
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: [[TMP1:%.*]] = and i4 [[N0]], [[M:%.*]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[TMP1]], [[X]]
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; CHECK-NEXT: call void @use4(i4 [[N0]])
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; CHECK-NEXT: ret i4 [[R]]
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;
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%im = xor i4 %m, -1
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%n0 = xor i4 %x, %y ; two uses of %n0, THIS IS OK!
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%n1 = and i4 %n0, %im
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%r = xor i4 %n1, %y
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call void @use4(i4 %n0)
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ret i4 %r
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}
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define i4 @n_oneuse_A (i4 %x, i4 %y, i4 %m) {
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; CHECK-LABEL: @n_oneuse_A(
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; CHECK-NEXT: [[IM:%.*]] = xor i4 [[M:%.*]], -1
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: [[N1:%.*]] = and i4 [[N0]], [[IM]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[N1]], [[Y]]
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; CHECK-NEXT: call void @use4(i4 [[N1]])
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; CHECK-NEXT: ret i4 [[R]]
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;
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%im = xor i4 %m, -1
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%n0 = xor i4 %x, %y
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%n1 = and i4 %n0, %im ; two uses of %n1, which is going to be replaced
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%r = xor i4 %n1, %y
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call void @use4(i4 %n1)
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ret i4 %r
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}
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define i4 @n_oneuse_AD (i4 %x, i4 %y, i4 %m) {
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; CHECK-LABEL: @n_oneuse_AD(
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; CHECK-NEXT: [[IM:%.*]] = xor i4 [[M:%.*]], -1
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: [[N1:%.*]] = and i4 [[N0]], [[IM]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[N1]], [[Y]]
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; CHECK-NEXT: call void @use4(i4 [[N0]])
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; CHECK-NEXT: call void @use4(i4 [[N1]])
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; CHECK-NEXT: ret i4 [[R]]
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;
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%im = xor i4 %m, -1
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%n0 = xor i4 %x, %y
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%n1 = and i4 %n0, %im ; two uses of %n1, which is going to be replaced
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%r = xor i4 %n1, %y
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call void @use4(i4 %n0)
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call void @use4(i4 %n1)
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ret i4 %r
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}
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; Some third variable is used
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define i4 @n_third_var (i4 %x, i4 %y, i4 %z, i4 %m) {
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; CHECK-LABEL: @n_third_var(
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; CHECK-NEXT: [[IM:%.*]] = xor i4 [[M:%.*]], -1
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: [[N1:%.*]] = and i4 [[N0]], [[IM]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[N1]], [[Z:%.*]]
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; CHECK-NEXT: ret i4 [[R]]
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;
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%im = xor i4 %m, -1
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%n0 = xor i4 %x, %y
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%n1 = and i4 %n0, %im
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%r = xor i4 %n1, %z ; not %x or %y
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ret i4 %r
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}
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define i4 @n_badxor (i4 %x, i4 %y, i4 %m) {
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; CHECK-LABEL: @n_badxor(
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; CHECK-NEXT: [[IM:%.*]] = xor i4 [[M:%.*]], 1
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; CHECK-NEXT: [[N0:%.*]] = xor i4 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: [[N1:%.*]] = and i4 [[N0]], [[IM]]
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; CHECK-NEXT: [[R:%.*]] = xor i4 [[N1]], [[Y]]
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; CHECK-NEXT: ret i4 [[R]]
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;
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%im = xor i4 %m, 1 ; not -1
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%n0 = xor i4 %x, %y
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%n1 = and i4 %n0, %im
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%r = xor i4 %n1, %y
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ret i4 %r
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}
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