9d57a77b81
If we are truncating from a i32 source before comparing the result against zero, then see if we can directly compare the source value against zero. If the upper (truncated) bits are known to be zero then we can compare against that, hopefully increasing the chances of us folding the compare into a EFLAG result of the source's operation. Fixes PR49028. Differential Revision: https://reviews.llvm.org/D100491
28 lines
857 B
LLVM
28 lines
857 B
LLVM
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
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; RUN: llc < %s -mtriple=i686-unknown | FileCheck %s --check-prefix=X86
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; RUN: llc < %s -mtriple=x86_64-unknown | FileCheck %s --check-prefix=X64
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define zeroext i16 @PR49028(i16 zeroext %0, i8* %1) {
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; X86-LABEL: PR49028:
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; X86: # %bb.0:
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; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
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; X86-NEXT: movzwl {{[0-9]+}}(%esp), %eax
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; X86-NEXT: shrl %eax
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; X86-NEXT: sete (%ecx)
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; X86-NEXT: # kill: def $ax killed $ax killed $eax
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; X86-NEXT: retl
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;
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; X64-LABEL: PR49028:
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; X64: # %bb.0:
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; X64-NEXT: movl %edi, %eax
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; X64-NEXT: shrl %eax
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; X64-NEXT: sete (%rsi)
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; X64-NEXT: # kill: def $ax killed $ax killed $eax
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; X64-NEXT: retq
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%3 = lshr i16 %0, 1
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%4 = icmp eq i16 %3, 0
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%5 = zext i1 %4 to i8
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store i8 %5, i8* %1, align 1
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ret i16 %3
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}
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