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.
195 lines
5.4 KiB
LLVM
195 lines
5.4 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -passes=instcombine -S < %s | FileCheck %s
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declare void @use(i8)
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define i8 @basic(i8 %x, i8 %y) {
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; CHECK-LABEL: @basic(
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; CHECK-NEXT: [[NOTA:%.*]] = sub i8 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i8 [[NOTA]]
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;
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%notx = xor i8 %x, -1
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%a = add i8 %notx, %y
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%nota = xor i8 %a, -1
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ret i8 %nota
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}
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define i8 @basic_com_add(i8 %x, i8 %y) {
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; CHECK-LABEL: @basic_com_add(
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; CHECK-NEXT: [[NOTA:%.*]] = sub i8 [[Y:%.*]], [[X:%.*]]
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; CHECK-NEXT: ret i8 [[NOTA]]
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;
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%noty = xor i8 %y, -1
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%a = add i8 %x, %noty
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%nota = xor i8 %a, -1
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ret i8 %nota
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}
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define i8 @basic_use_xor(i8 %x, i8 %y) {
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; CHECK-LABEL: @basic_use_xor(
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; CHECK-NEXT: [[NOTX:%.*]] = xor i8 [[X:%.*]], -1
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; CHECK-NEXT: call void @use(i8 [[NOTX]])
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; CHECK-NEXT: [[NOTA:%.*]] = sub i8 [[X]], [[Y:%.*]]
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; CHECK-NEXT: ret i8 [[NOTA]]
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;
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%notx = xor i8 %x, -1
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call void @use(i8 %notx)
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%a = add i8 %notx, %y
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%nota = xor i8 %a, -1
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ret i8 %nota
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}
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define i8 @basic_use_add(i8 %x, i8 %y) {
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; CHECK-LABEL: @basic_use_add(
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; CHECK-NEXT: [[NOTX:%.*]] = xor i8 [[X:%.*]], -1
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; CHECK-NEXT: [[A:%.*]] = add i8 [[Y:%.*]], [[NOTX]]
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; CHECK-NEXT: call void @use(i8 [[A]])
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; CHECK-NEXT: [[NOTA:%.*]] = sub i8 [[X]], [[Y]]
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; CHECK-NEXT: ret i8 [[NOTA]]
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;
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%notx = xor i8 %x, -1
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%a = add i8 %notx, %y
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call void @use(i8 %a)
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%nota = xor i8 %a, -1
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ret i8 %nota
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}
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define i8 @basic_use_both(i8 %x, i8 %y) {
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; CHECK-LABEL: @basic_use_both(
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; CHECK-NEXT: [[NOTX:%.*]] = xor i8 [[X:%.*]], -1
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; CHECK-NEXT: call void @use(i8 [[NOTX]])
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; CHECK-NEXT: [[A:%.*]] = add i8 [[Y:%.*]], [[NOTX]]
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; CHECK-NEXT: call void @use(i8 [[A]])
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; CHECK-NEXT: [[NOTA:%.*]] = sub i8 [[X]], [[Y]]
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; CHECK-NEXT: ret i8 [[NOTA]]
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;
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%notx = xor i8 %x, -1
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call void @use(i8 %notx)
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%a = add i8 %notx, %y
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call void @use(i8 %a)
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%nota = xor i8 %a, -1
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ret i8 %nota
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}
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define i8 @basic_preserve_nsw(i8 %x, i8 %y) {
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; CHECK-LABEL: @basic_preserve_nsw(
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; CHECK-NEXT: [[NOTA:%.*]] = sub nsw i8 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i8 [[NOTA]]
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;
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%notx = xor i8 %x, -1
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%a = add nsw i8 %notx, %y
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%nota = xor i8 %a, -1
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ret i8 %nota
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}
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define i8 @basic_preserve_nuw(i8 %x, i8 %y) {
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; CHECK-LABEL: @basic_preserve_nuw(
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; CHECK-NEXT: [[NOTA:%.*]] = sub nuw i8 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i8 [[NOTA]]
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;
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%notx = xor i8 %x, -1
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%a = add nuw i8 %notx, %y
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%nota = xor i8 %a, -1
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ret i8 %nota
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}
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define i8 @basic_preserve_nuw_nsw(i8 %x, i8 %y) {
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; CHECK-LABEL: @basic_preserve_nuw_nsw(
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; CHECK-NEXT: [[NOTA:%.*]] = sub nuw nsw i8 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i8 [[NOTA]]
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;
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%notx = xor i8 %x, -1
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%a = add nuw nsw i8 %notx, %y
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%nota = xor i8 %a, -1
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ret i8 %nota
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}
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define <4 x i32> @vector_test(<4 x i32> %x, <4 x i32> %y) {
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; CHECK-LABEL: @vector_test(
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; CHECK-NEXT: [[NOTA:%.*]] = sub <4 x i32> [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret <4 x i32> [[NOTA]]
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;
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%notx = xor <4 x i32> %x, <i32 -1, i32 -1, i32 -1, i32 -1>
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%a = add <4 x i32> %notx, %y
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%nota = xor <4 x i32> %a, <i32 -1, i32 -1, i32 -1, i32 -1>
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ret <4 x i32> %nota
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}
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define <4 x i32> @vector_test_poison(<4 x i32> %x, <4 x i32> %y) {
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; CHECK-LABEL: @vector_test_poison(
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; CHECK-NEXT: [[NOTA:%.*]] = sub <4 x i32> [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret <4 x i32> [[NOTA]]
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;
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%notx = xor <4 x i32> %x, <i32 -1, i32 poison, i32 poison, i32 -1>
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%a = add <4 x i32> %notx, %y
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%nota = xor <4 x i32> %a, <i32 -1, i32 -1, i32 poison, i32 poison>
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ret <4 x i32> %nota
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}
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define <4 x i32> @vector_test_poison_nsw_nuw(<4 x i32> %x, <4 x i32> %y) {
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; CHECK-LABEL: @vector_test_poison_nsw_nuw(
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; CHECK-NEXT: [[NOTA:%.*]] = sub nuw nsw <4 x i32> [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret <4 x i32> [[NOTA]]
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;
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%notx = xor <4 x i32> %x, <i32 -1, i32 poison, i32 poison, i32 -1>
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%a = add nsw nuw <4 x i32> %notx, %y
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%nota = xor <4 x i32> %a, <i32 -1, i32 -1, i32 poison, i32 poison>
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ret <4 x i32> %nota
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}
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define i32 @pr50308(i1 %c1, i32 %v1, i32 %v2, i32 %v3) {
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; CHECK-LABEL: @pr50308(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br i1 [[C1:%.*]], label [[COND_TRUE:%.*]], label [[COND_END:%.*]]
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; CHECK: cond.true:
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; CHECK-NEXT: [[TMP0:%.*]] = sub i32 -2, [[V1:%.*]]
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; CHECK-NEXT: [[ADD1_NEG:%.*]] = xor i32 [[TMP0]], [[V2:%.*]]
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; CHECK-NEXT: br label [[COND_END]]
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; CHECK: cond.end:
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; CHECK-NEXT: [[COND_NEG:%.*]] = phi i32 [ [[ADD1_NEG]], [[COND_TRUE]] ], [ 0, [[ENTRY:%.*]] ]
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; CHECK-NEXT: [[SUB:%.*]] = add i32 [[COND_NEG]], [[V3:%.*]]
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; CHECK-NEXT: ret i32 [[SUB]]
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;
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entry:
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br i1 %c1, label %cond.true, label %cond.end
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cond.true:
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%add = add nsw i32 1, %v1
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%xor = xor i32 %add, %v2
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%add1 = add nsw i32 1, %xor
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br label %cond.end
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cond.end:
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%cond = phi i32 [ %add1, %cond.true ], [ 0, %entry ]
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%sub = sub nsw i32 %v3, %cond
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ret i32 %sub
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}
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@g = extern_weak global i32
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define void @pr50370(i32 %x) {
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; CHECK-LABEL: @pr50370(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: store i32 poison, ptr undef, align 4
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; CHECK-NEXT: ret void
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;
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entry:
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%xor = xor i32 %x, 1
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%cmp = icmp eq ptr @g, null
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%ext = zext i1 %cmp to i32
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%or = or i32 %ext, 1
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%or4 = or i32 %or, 65536
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%B6 = ashr i32 65536, %or4
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%B15 = srem i32 %B6, %xor
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%B20 = sdiv i32 %or4, 2147483647
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%B22 = add i32 %B15, %B20
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%B14 = srem i32 %B6, %B22
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%B12 = add i32 %B15, %B6
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%B8 = shl i32 %B20, %B14
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%B2 = xor i32 %B12, %B8
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%B3 = or i32 %B12, undef
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%B = xor i32 %B2, %B3
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store i32 %B, ptr undef, align 4
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ret void
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}
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