1228becf7d
This patch deduces `noundef` attributes for return values. IIUC, a function returns `noundef` values iff all of its return values are guaranteed not to be `undef` or `poison`. Definition of `noundef` from LangRef: ``` noundef This attribute applies to parameters and return values. If the value representation contains any undefined or poison bits, the behavior is undefined. Note that this does not refer to padding introduced by the type’s storage representation. ``` Alive2: https://alive2.llvm.org/ce/z/g8Eis6 Compile-time impact: http://llvm-compile-time-tracker.com/compare.php?from=30dcc33c4ea3ab50397a7adbe85fe977d4a400bd&to=c5e8738d4bfbf1e97e3f455fded90b791f223d74&stat=instructions:u |stage1-O3|stage1-ReleaseThinLTO|stage1-ReleaseLTO-g|stage1-O0-g|stage2-O3|stage2-O0-g|stage2-clang| |--|--|--|--|--|--|--| |+0.01%|+0.01%|-0.01%|+0.01%|+0.03%|-0.04%|+0.01%| The motivation of this patch is to reduce the number of `freeze` insts and enable more optimizations.
30 lines
1.3 KiB
LLVM
30 lines
1.3 KiB
LLVM
; REQUIRES: x86
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; RUN: rm -fr %T/savetemps
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; RUN: mkdir %T/savetemps
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; RUN: llvm-as -o %T/savetemps/savetemps.obj %s
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; RUN: lld-link /out:%T/savetemps/savetemps.exe /entry:main \
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; RUN: /subsystem:console %T/savetemps/savetemps.obj
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; RUN: not llvm-dis -o - %T/savetemps/savetemps.exe.0.0.preopt.bc
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; RUN: not llvm-dis -o - %T/savetemps/savetemps.exe.0.2.internalize.bc
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; RUN: not llvm-dis -o - %T/savetemps/savetemps.exe.0.4.opt.bc
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; RUN: not llvm-dis -o - %T/savetemps/savetemps.exe.0.5.precodegen.bc
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; RUN: not llvm-objdump -s %T/savetemps/savetemps.exe.lto.obj
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; RUN: lld-link /lldsavetemps /out:%T/savetemps/savetemps.exe /entry:main \
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; RUN: /subsystem:console %T/savetemps/savetemps.obj
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; RUN: llvm-dis -o - %T/savetemps/savetemps.exe.0.0.preopt.bc | FileCheck %s
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; RUN: llvm-dis -o - %T/savetemps/savetemps.exe.0.2.internalize.bc | FileCheck %s
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; RUN: llvm-dis -o - %T/savetemps/savetemps.exe.0.4.opt.bc | FileCheck %s
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; RUN: llvm-dis -o - %T/savetemps/savetemps.exe.0.5.precodegen.bc | FileCheck %s
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; RUN: llvm-objdump -s %T/savetemps/savetemps.exe.lto.obj | \
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; RUN: FileCheck --check-prefix=CHECK-OBJDUMP %s
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; CHECK: define {{(noundef )?}}i32 @main()
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; CHECK-OBJDUMP: file format coff
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target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-pc-windows-msvc"
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define i32 @main() {
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ret i32 0
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}
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