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22309ec191
Summary: X86ISelDAGToDAG tries to analyze ANDs compared with 0 to optimize to narrower immediates using subregisters. I don't think we should be optimizing to 16-bit test instructions. It goes against our normal behavior of promoting i16 operations to i32. It only saves one byte due to the need to add a 0x66 prefix. I think it would also be subject to a length changing prefix penalty in the decoders on Intel CPUs. Reviewers: RKSimon, zvi, spatel Reviewed By: spatel Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D38273 llvm-svn: 314474
24 lines
920 B
LLVM
24 lines
920 B
LLVM
; RUN: llc < %s | FileCheck %s
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; Codegen shouldn't reduce the comparison down to testb $-1, %al
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; because that changes the result of the signed test.
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; PR5132
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; CHECK: testl $255, %eax
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target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
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target triple = "i386-apple-darwin10.0"
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@g_14 = global i8 -6, align 1 ; <i8*> [#uses=1]
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declare i32 @func_16(i8 signext %p_19, i32 %p_20) nounwind
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define i32 @func_35(i64 %p_38) nounwind ssp {
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entry:
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%tmp = load i8, i8* @g_14 ; <i8> [#uses=2]
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%conv = zext i8 %tmp to i32 ; <i32> [#uses=1]
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%cmp = icmp sle i32 1, %conv ; <i1> [#uses=1]
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%conv2 = zext i1 %cmp to i32 ; <i32> [#uses=1]
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%call = call i32 @func_16(i8 signext %tmp, i32 %conv2) ssp ; <i32> [#uses=1]
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ret i32 1
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}
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