[llvm] r268512 - [SimplifyCFG] isSafeToSpeculateStore now ignores debug info
David Blaikie via llvm-commits
llvm-commits at lists.llvm.org
Wed May 4 08:51:27 PDT 2016
On Wed, May 4, 2016 at 8:40 AM, Hans Wennborg via llvm-commits <
llvm-commits at lists.llvm.org> wrote:
> Author: hans
> Date: Wed May 4 10:40:57 2016
> New Revision: 268512
>
> URL: http://llvm.org/viewvc/llvm-project?rev=268512&view=rev
> Log:
> [SimplifyCFG] isSafeToSpeculateStore now ignores debug info
>
> This patch fixes PR27615.
>
> @llvm.dbg.value instructions no longer count towards the maximum number of
> instructions to look back at in the instruction list when searching for a
> store instruction. This should make the output consistent between debug and
> non-debug build.
>
> Patch by Henric Karlsson <henric.karlsson at ericsson.com>!
>
> Differential Revision: http://reviews.llvm.org/D19912
>
> Added:
> llvm/trunk/test/Transforms/SimplifyCFG/PR27615-simplify-cond-br.ll
> Modified:
> llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
>
> Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=268512&r1=268511&r2=268512&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
> +++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Wed May 4 10:40:57
> 2016
> @@ -1448,10 +1448,14 @@ static Value *isSafeToSpeculateStore(Ins
> Value *StorePtr = StoreToHoist->getPointerOperand();
>
> // Look for a store to the same pointer in BrBB.
> - unsigned MaxNumInstToLookAt = 10;
> + unsigned MaxNumInstToLookAt = 9;
> for (BasicBlock::reverse_iterator RI = BrBB->rbegin(),
> - RE = BrBB->rend(); RI != RE && (--MaxNumInstToLookAt); ++RI) {
> + RE = BrBB->rend(); RI != RE && MaxNumInstToLookAt; ++RI) {
> Instruction *CurI = &*RI;
> + // Skip debug info.
> + if (isa<DbgInfoIntrinsic>(CurI))
> + continue;
> + --MaxNumInstToLookAt;
>
> // Could be calling an instruction that effects memory like free().
> if (CurI->mayHaveSideEffects() && !isa<StoreInst>(CurI))
>
> Added: llvm/trunk/test/Transforms/SimplifyCFG/PR27615-simplify-cond-br.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/PR27615-simplify-cond-br.ll?rev=268512&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/SimplifyCFG/PR27615-simplify-cond-br.ll
> (added)
> +++ llvm/trunk/test/Transforms/SimplifyCFG/PR27615-simplify-cond-br.ll Wed
> May 4 10:40:57 2016
> @@ -0,0 +1,68 @@
> +; RUN: opt -S -simplifycfg -strip-debug < %s | FileCheck %s
> +; RUN: opt -S -simplifycfg < %s | FileCheck %s
> +
> +; Test case for BUG-27615
>
I was going to say that we usually refer to bugs by PRXXXXX, but then I saw
you did in the file name - so perhaps this comment doesn't add much?
Also, I'd tend to prefer a test case that just describes what it tests
(both in name & text) standalone, rather than needing to refer to a bug to
understand the intent. But that's not a strong habit within the project, so
it's hardly something I'll advocate strongly for.
> +; Test that simplify cond branch produce same result for debug and
> non-debug builds
> +; CHECK: select i1 %or.cond, i32 -1, i32 5
> +; CHECK-NOT: bb1:
> +
> +; ModuleID = './csmith107.i.debug.ll'
> +source_filename = "./csmith107.i.debug.ll"
> +
> + at a = global i16 0
> + at b = global i32 0
> + at c = global i16* null
> +
> +
> +; Function Attrs: nounwind
> +define i16 @fn1() #3 !dbg !15 {
> +bb2:
> + store i32 -1, i32* @b, align 1
> + %_tmp1.pre = load i16, i16* @a, align 1, !dbg !19
> + %_tmp2.pre = load i16*, i16** @c, align 1
> + tail call void @llvm.dbg.value(metadata i16 6, i64 0, metadata !22,
> metadata !23), !dbg !24
> + tail call void @llvm.dbg.value(metadata i16 %_tmp1.pre, i64 0, metadata
> !25, metadata !23), !dbg !19
> + %_tmp3 = load i16, i16* %_tmp2.pre, align 1
> + %_tmp4 = icmp ne i16 %_tmp3, 0
> + %_tmp6 = icmp ne i16 %_tmp1.pre, 0
> + %or.cond = and i1 %_tmp6, %_tmp4
> + br i1 %or.cond, label %bb5, label %bb1
> +
> +bb1: ; preds = %bb2
> + store i32 5, i32* @b, align 1
> + br label %bb5
> +
> +bb5: ; preds = %bb1, %bb2
> + ret i16 0
> +}
> +
> +; Function Attrs: nounwind readnone
> +declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #4
> +
> +!llvm.dbg.cu = !{!0}
> +!llvm.module.flags = !{!12, !13}
> +
> +!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer:
> "FlexC Compiler v6.36 (LLVM)", isOptimized: false, runtimeVersion: 0,
> emissionKind: FullDebug, enums: !2, retainedTypes: !2, globals: !3)
> +!1 = !DIFile(filename: "csmith107.i.c", directory: "/tmp")
> +!2 = !{}
> +!3 = !{!4, !6, !10}
> +!4 = !DIGlobalVariable(name: "a", scope: null, file: !1, line: 2, type:
> !5, isLocal: false, isDefinition: true, variable: i16* @a)
> +!5 = !DIBasicType(name: "int", size: 16, align: 16, encoding:
> DW_ATE_signed)
> +!6 = !DIGlobalVariable(name: "b", scope: null, file: !1, line: 3, type:
> !7, isLocal: false, isDefinition: true, variable: i32* @b)
> +!7 = !DIDerivedType(tag: DW_TAG_typedef, name: "uint32_t", file: !1,
> line: 1, baseType: !8)
> +!8 = !DIDerivedType(tag: DW_TAG_typedef, name: "__u32_t", file: !1,
> baseType: !9)
> +!9 = !DIBasicType(name: "unsigned long", size: 32, align: 16, encoding:
> DW_ATE_unsigned)
> +!10 = !DIGlobalVariable(name: "c", scope: null, file: !1, line: 4, type:
> !11, isLocal: false, isDefinition: true, variable: i16** @c)
> +!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !5, size: 16,
> align: 16)
> +!12 = !{i32 2, !"Dwarf Version", i32 4}
> +!13 = !{i32 2, !"Debug Info Version", i32 3}
> +!15 = distinct !DISubprogram(name: "fn1", scope: !1, file: !1, line: 5,
> type: !16, isLocal: false, isDefinition: true, scopeLine: 5, isOptimized:
> false, unit: !0, variables: !2)
> +!16 = !DISubroutineType(types: !17)
> +!17 = !{!5}
> +!19 = !DILocation(line: 8, column: 16, scope: !20)
> +!20 = !DILexicalBlock(scope: !15, file: !1, line: 7, column: 29)
> +!22 = !DILocalVariable(name: "d", scope: !20, line: 8, type: !5)
> +!23 = !DIExpression()
> +!24 = !DILocation(line: 8, column: 9, scope: !20)
> +!25 = !DILocalVariable(name: "e", scope: !20, line: 8, type: !5)
> +
>
>
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