f37ab15254
Infer the 'exact' flag on an 'lshr' or 'ashr' instruction when the shift amount is computed via a 'cttz' intrinsic on the same operand. Proof: https://alive2.llvm.org/ce/z/CQR2PG Fixes #131444.
42 lines
1.4 KiB
LLVM
42 lines
1.4 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
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; RUN: opt -passes=instcombine -S < %s | FileCheck %s
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declare i32 @llvm.cttz.i32(i32, i1)
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define i32 @test_cttz_lshr(i32 %x) {
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; CHECK-LABEL: define i32 @test_cttz_lshr(
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; CHECK-SAME: i32 [[X:%.*]]) {
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; CHECK-NEXT: [[CTTZ:%.*]] = call range(i32 0, 33) i32 @llvm.cttz.i32(i32 [[X]], i1 true)
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; CHECK-NEXT: [[SH:%.*]] = lshr exact i32 [[X]], [[CTTZ]]
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; CHECK-NEXT: ret i32 [[SH]]
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;
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%cttz = call i32 @llvm.cttz.i32(i32 %x, i1 false)
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%sh = lshr i32 %x, %cttz
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ret i32 %sh
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}
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define i32 @test_cttz_ashr(i32 %x) {
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; CHECK-LABEL: define i32 @test_cttz_ashr(
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; CHECK-SAME: i32 [[X:%.*]]) {
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; CHECK-NEXT: [[CTTZ:%.*]] = call range(i32 0, 33) i32 @llvm.cttz.i32(i32 [[X]], i1 true)
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; CHECK-NEXT: [[SH:%.*]] = ashr exact i32 [[X]], [[CTTZ]]
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; CHECK-NEXT: ret i32 [[SH]]
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;
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%cttz = call i32 @llvm.cttz.i32(i32 %x, i1 true)
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%sh = ashr i32 %x, %cttz
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ret i32 %sh
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}
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define i32 @test_cttz_diff_operand(i32 %x, i32 %y) {
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; CHECK-LABEL: define i32 @test_cttz_diff_operand(
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; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
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; CHECK-NEXT: [[CTTZ:%.*]] = call range(i32 0, 33) i32 @llvm.cttz.i32(i32 [[Y]], i1 true)
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; CHECK-NEXT: [[SH:%.*]] = lshr i32 [[X]], [[CTTZ]]
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; CHECK-NEXT: ret i32 [[SH]]
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;
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%cttz = call i32 @llvm.cttz.i32(i32 %y, i1 true)
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%sh = lshr i32 %x, %cttz
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ret i32 %sh
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}
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