d81db0e5f5
The exact flag basically allows us to set an upper bound on shift amount when we have a known 1 in `LHS`. Typically we deduce exact using knownbits (on non-exact incoming shifts), so this is particularly impactful, but may be useful in some circumstances. Closes #84254
21 lines
493 B
LLVM
21 lines
493 B
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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define i8 @simplify_lshr_with_exact(i8 %x) {
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; CHECK-LABEL: @simplify_lshr_with_exact(
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; CHECK-NEXT: ret i8 2
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;
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%shr = lshr exact i8 6, %x
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%r = and i8 %shr, 2
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ret i8 %r
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}
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define i8 @simplify_ashr_with_exact(i8 %x) {
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; CHECK-LABEL: @simplify_ashr_with_exact(
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; CHECK-NEXT: ret i8 2
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;
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%shr = ashr exact i8 -122, %x
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%r = and i8 %shr, 2
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ret i8 %r
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}
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