[llvm] r245588 - Fix a debug location handling bug in GVN.
Björn Steinbrink via llvm-commits
llvm-commits at lists.llvm.org
Fri Nov 6 05:35:51 PST 2015
Hi,
can we get this into 3.7.1? The bug that is fixed here is a regression
from 3.6 and bootstrapping Rust with debug info enabled triggers this
bug, so we currently can't build with debug info enabled with an
upstream 3.7 release which is unfortunate.
Thanks,
Björn
On 2015.08.20 18:23:57 -0000, Adrian Prantl via llvm-commits wrote:
> Author: adrian
> Date: Thu Aug 20 13:23:56 2015
> New Revision: 245588
>
> URL: http://llvm.org/viewvc/llvm-project?rev=245588&view=rev
> Log:
> Fix a debug location handling bug in GVN.
> Caught by the famous "DebugLoc describes the currect SubProgram" assertion.
>
> When GVN is removing a nonlocal load it updates the debug location of the
> SSA value it replaced the load with with the one of the load. In the
> testcase this actually overwrites a valid debug location with an empty one.
>
> In reality GVN has to make an arbitrary choice between two equally valid
> debug locations. This patch changes to behavior to only update the
> location if the value doesn't already have a debug location.
>
> Added:
> llvm/trunk/test/DebugInfo/gvn.ll
> Modified:
> llvm/trunk/lib/Transforms/Scalar/GVN.cpp
>
> Modified: llvm/trunk/lib/Transforms/Scalar/GVN.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/GVN.cpp?rev=245588&r1=245587&r2=245588&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/GVN.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp Thu Aug 20 13:23:56 2015
> @@ -1744,7 +1744,8 @@ bool GVN::processNonLocalLoad(LoadInst *
> if (isa<PHINode>(V))
> V->takeName(LI);
> if (Instruction *I = dyn_cast<Instruction>(V))
> - I->setDebugLoc(LI->getDebugLoc());
> + if (LI->getDebugLoc())
> + I->setDebugLoc(LI->getDebugLoc());
> if (V->getType()->getScalarType()->isPointerTy())
> MD->invalidateCachedPointerInfo(V);
> markInstructionForDeletion(LI);
>
> Added: llvm/trunk/test/DebugInfo/gvn.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/gvn.ll?rev=245588&view=auto
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/gvn.ll (added)
> +++ llvm/trunk/test/DebugInfo/gvn.ll Thu Aug 20 13:23:56 2015
> @@ -0,0 +1,135 @@
> +; RUN: opt < %s -O2 -gvn -S | FileCheck %s
> +;
> +; Produced at -O2 from:
> +; struct context {
> +; int cur_pid
> +; };
> +; int a, b, c, f, d;
> +; int pid_for_task(int);
> +; sample(struct context *p1)
> +; {
> +; if (c)
> +; b = a;
> +; if (a && p1->cur_pid)
> +; sample_internal();
> +; }
> +; callback() {
> +; f = pid_for_task(d);
> +; sample(&f);
> +; }
> +
> +target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
> +target triple = "arm64-apple-ios"
> +
> +%struct.context = type { i32 }
> +
> + at c = common global i32 0, align 4
> + at a = common global i32 0, align 4
> + at b = common global i32 0, align 4
> + at d = common global i32 0, align 4
> + at f = common global i32 0, align 4
> +
> +; Function Attrs: nounwind
> +declare i32 @sample_internal(...)
> +
> +; Function Attrs: nounwind
> +define i32 @callback() #0 {
> +entry:
> + %0 = load i32, i32* @d, align 4, !dbg !37
> +
> + ; Verify that the call still has a debug location after GVN.
> + ; CHECK: %call = tail call i32 @pid_for_task(i32 %0) #{{[0-9]}}, !dbg
> + %call = tail call i32 @pid_for_task(i32 %0) #3, !dbg !37
> +
> + store i32 %call, i32* @f, align 4, !dbg !37
> + tail call void @llvm.dbg.value(metadata %struct.context* bitcast (i32* @f to %struct.context*), i64 0, metadata !25, metadata !26) #3, !dbg !38
> + %1 = load i32, i32* @c, align 4, !dbg !40
> + %tobool.i = icmp eq i32 %1, 0, !dbg !40
> + %.pr.i = load i32, i32* @a, align 4, !dbg !41
> + br i1 %tobool.i, label %if.end.i, label %if.then.i, !dbg !42
> +
> +if.then.i: ; preds = %entry
> + store i32 %.pr.i, i32* @b, align 4, !dbg !43
> + br label %if.end.i, !dbg !43
> +
> +if.end.i: ; preds = %if.then.i, %entry
> + %tobool1.i = icmp eq i32 %.pr.i, 0, !dbg !41
> +
> + ; This instruction has no debug location -- in this
> + ; particular case it was removed by a bug in SimplifyCFG.
> + %2 = load i32, i32* @f, align 4
> +
> + ; GVN is supposed to replace the load of @f with a direct reference to %call.
> + ; CHECK: %tobool2.i = icmp eq i32 %call, 0, !dbg
> + %tobool2.i = icmp eq i32 %2, 0, !dbg !41
> +
> + %or.cond = or i1 %tobool1.i, %tobool2.i, !dbg !41
> + br i1 %or.cond, label %sample.exit, label %if.then.3.i, !dbg !41
> +
> +if.then.3.i: ; preds = %if.end.i
> + %call.i = tail call i32 bitcast (i32 (...)* @sample_internal to i32 ()*)() #3, !dbg !44
> + br label %sample.exit, !dbg !44
> +
> +sample.exit: ; preds = %if.end.i, %if.then.3.i
> + ret i32 undef, !dbg !45
> +}
> +
> +declare i32 @pid_for_task(i32) #1
> +
> +; Function Attrs: nounwind readnone
> +declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #2
> +
> +attributes #0 = { nounwind }
> +attributes #2 = { nounwind readnone }
> +attributes #3 = { nounwind }
> +
> +!llvm.dbg.cu = !{!0}
> +!llvm.module.flags = !{!22, !23}
> +!llvm.ident = !{!24}
> +
> +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.8.0 (trunk 244473) (llvm/trunk 244644)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3, globals: !16)
> +!1 = !DIFile(filename: "test.c", directory: "/")
> +!2 = !{}
> +!3 = !{!4, !13}
> +!4 = !DISubprogram(name: "sample", scope: !5, file: !5, line: 6, type: !6, isLocal: false, isDefinition: true, scopeLine: 7, flags: DIFlagPrototyped, isOptimized: false, variables: !2)
> +!5 = !DIFile(filename: "test.i", directory: "/")
> +!6 = !DISubroutineType(types: !7)
> +!7 = !{!8, !9}
> +!8 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
> +!9 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 64, align: 64)
> +!10 = !DICompositeType(tag: DW_TAG_structure_type, name: "context", file: !5, line: 1, size: 32, align: 32, elements: !11)
> +!11 = !{!12}
> +!12 = !DIDerivedType(tag: DW_TAG_member, name: "cur_pid", scope: !10, file: !5, line: 2, baseType: !8, size: 32, align: 32)
> +!13 = !DISubprogram(name: "callback", scope: !5, file: !5, line: 13, type: !14, isLocal: false, isDefinition: true, scopeLine: 13, isOptimized: false, function: i32 ()* @callback, variables: !2)
> +!14 = !DISubroutineType(types: !15)
> +!15 = !{!8}
> +!16 = !{!17, !18, !19, !20, !21}
> +!17 = !DIGlobalVariable(name: "a", scope: !0, file: !5, line: 4, type: !8, isLocal: false, isDefinition: true, variable: i32* @a)
> +!18 = !DIGlobalVariable(name: "b", scope: !0, file: !5, line: 4, type: !8, isLocal: false, isDefinition: true, variable: i32* @b)
> +!19 = !DIGlobalVariable(name: "c", scope: !0, file: !5, line: 4, type: !8, isLocal: false, isDefinition: true, variable: i32* @c)
> +!20 = !DIGlobalVariable(name: "f", scope: !0, file: !5, line: 4, type: !8, isLocal: false, isDefinition: true, variable: i32* @f)
> +!21 = !DIGlobalVariable(name: "d", scope: !0, file: !5, line: 4, type: !8, isLocal: false, isDefinition: true, variable: i32* @d)
> +!22 = !{i32 2, !"Dwarf Version", i32 2}
> +!23 = !{i32 2, !"Debug Info Version", i32 3}
> +!24 = !{!"clang version 3.8.0 (trunk 244473) (llvm/trunk 244644)"}
> +!25 = !DILocalVariable(name: "p1", arg: 1, scope: !4, file: !5, line: 6, type: !9)
> +!26 = !DIExpression()
> +!27 = !DILocation(line: 6, scope: !4)
> +!28 = !DILocation(line: 8, scope: !29)
> +!29 = distinct !DILexicalBlock(scope: !4, file: !5, line: 8)
> +!30 = !DILocation(line: 10, scope: !31)
> +!31 = distinct !DILexicalBlock(scope: !4, file: !5, line: 10)
> +!32 = !DILocation(line: 8, scope: !4)
> +!33 = !DILocation(line: 9, scope: !29)
> +!34 = !DILocation(line: 10, scope: !4)
> +!35 = !DILocation(line: 11, scope: !31)
> +!36 = !DILocation(line: 12, scope: !4)
> +!37 = !DILocation(line: 14, scope: !13)
> +!38 = !DILocation(line: 6, scope: !4, inlinedAt: !39)
> +!39 = distinct !DILocation(line: 15, scope: !13)
> +!40 = !DILocation(line: 8, scope: !29, inlinedAt: !39)
> +!41 = !DILocation(line: 10, scope: !31, inlinedAt: !39)
> +!42 = !DILocation(line: 8, scope: !4, inlinedAt: !39)
> +!43 = !DILocation(line: 9, scope: !29, inlinedAt: !39)
> +!44 = !DILocation(line: 11, scope: !31, inlinedAt: !39)
> +!45 = !DILocation(line: 16, scope: !13)
>
>
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