[llvm-branch-commits] [llvm] 6464c4a - [LiveDebugVariables] Strip all debug instructions from nodebug functions
Robert Lougher via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Thu Nov 26 06:36:40 PST 2020
Author: Robert Lougher
Date: 2020-11-26T14:30:18Z
New Revision: 6464c4a170173a2b476ff4be6e160836032b68fe
URL: https://github.com/llvm/llvm-project/commit/6464c4a170173a2b476ff4be6e160836032b68fe
DIFF: https://github.com/llvm/llvm-project/commit/6464c4a170173a2b476ff4be6e160836032b68fe.diff
LOG: [LiveDebugVariables] Strip all debug instructions from nodebug functions
A crash/assertion failure in the greedy register allocator was tracked
down to a debug instr being passed to LiveIntervals::getInstructionIndex.
Normally this should not occur as debug instructions are collected and
removed by LiveDebugVariables before RA, and reinserted afterwards.
However, when a function has no debug info, LiveDebugVariables simply
strips any debug values that are present as they're not needed (this
situation will occur when a function with debug info is inlined into a
nodebug function). The problem is, it only removes DBG_VALUE instructions,
leaving DBG_LABELs (the cause of the crash).
This patch updates the LiveDebugVariables nodebug path to remove all debug
instructions. The test case verifies that DBG_VALUE/DBG_LABEL instructions
are present, and that they are stripped.
When -experimental-debug-variable-locations is enabled, certain variable
locations are represented by DBG_INSTR_REF instead of DBG_VALUE. The test
case verifies that a DBG_INSTR_REF is emitted by the option, and that it
is also stripped.
Differential Revision: https://reviews.llvm.org/D92127
Added:
llvm/test/DebugInfo/X86/live-debug-vars-nodebug.ll
Modified:
llvm/lib/CodeGen/LiveDebugVariables.cpp
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/LiveDebugVariables.cpp b/llvm/lib/CodeGen/LiveDebugVariables.cpp
index f4238bd38126..2325341070a3 100644
--- a/llvm/lib/CodeGen/LiveDebugVariables.cpp
+++ b/llvm/lib/CodeGen/LiveDebugVariables.cpp
@@ -1022,10 +1022,10 @@ bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
return Changed;
}
-static void removeDebugValues(MachineFunction &mf) {
+static void removeDebugInstrs(MachineFunction &mf) {
for (MachineBasicBlock &MBB : mf) {
for (auto MBBI = MBB.begin(), MBBE = MBB.end(); MBBI != MBBE; ) {
- if (!MBBI->isDebugValue()) {
+ if (!MBBI->isDebugInstr()) {
++MBBI;
continue;
}
@@ -1038,7 +1038,7 @@ bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
if (!EnableLDV)
return false;
if (!mf.getFunction().getSubprogram()) {
- removeDebugValues(mf);
+ removeDebugInstrs(mf);
return false;
}
if (!pImpl)
diff --git a/llvm/test/DebugInfo/X86/live-debug-vars-nodebug.ll b/llvm/test/DebugInfo/X86/live-debug-vars-nodebug.ll
new file mode 100644
index 000000000000..35d05392209d
--- /dev/null
+++ b/llvm/test/DebugInfo/X86/live-debug-vars-nodebug.ll
@@ -0,0 +1,101 @@
+; RUN: llc %s -mtriple=x86_64-unknown-unknown -o - -stop-before=finalize-isel \
+; RUN: | FileCheck %s --check-prefix=NORMAL-INPUT
+
+; RUN: llc %s -mtriple=x86_64-unknown-unknown -o - -stop-before=finalize-isel \
+; RUN: -experimental-debug-variable-locations \
+; RUN: | FileCheck %s --check-prefix=EXPER-INPUT
+
+; RUN: llc %s -mtriple=x86_64-unknown-unknown -o - -stop-after=livedebugvars \
+; RUN: | FileCheck %s --check-prefix=OUTPUT
+
+; RUN: llc %s -mtriple=x86_64-unknown-unknown -o - -stop-after=livedebugvars \
+; RUN: -experimental-debug-variable-locations \
+; RUN: | FileCheck %s --check-prefix=OUTPUT
+
+; This test checks that LiveDebugVariables strips all debug instructions
+; from nodebug functions. Such instructions occur when a function with debug
+; info is inlined into a nodebug function.
+
+; The test first verifies that DBG_VALUE/DBG_LABEL instructions are present in
+; the input to LiveDebugVariables. It then verifies that after the pass is ran
+; no debug instructions are present.
+
+; When -experimental-debug-variable-locations is enabled, certain variable
+; locations are represented by DBG_INSTR_REF instead of DBG_VALUE. The test
+; verifies that a DBG_INSTR_REF is emitted by the option, and that it is also
+; stripped.
+
+; Generated from:
+;
+; extern int foobar();
+;
+; int bar(int a) {
+; int b = 10;
+; b += foobar();
+; label:
+; if (a) goto label;
+; return b;
+; }
+;
+; __attribute__((nodebug))
+; int foo(int a) {
+; return bar(a);
+; }
+
+; NORMAL-INPUT-DAG: DBG_VALUE
+; NORMAL-INPUT-DAG: DBG_LABEL
+
+; EXPER-INPUT-DAG: DBG_INSTR_REF
+; EXPER-INPUT-DAG: DBG_LABEL
+
+; OUTPUT-NOT: DBG_VALUE
+; OUTPUT-NOT: DBG_INSTR_REF
+; OUTPUT-NOT: DBG_LABEL
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define dso_local i32 @_Z3fooi(i32 %a) local_unnamed_addr #0 {
+entry:
+ call void @llvm.dbg.value(metadata i32 %a, metadata !12, metadata !DIExpression()), !dbg !15
+ call void @llvm.dbg.value(metadata i32 10, metadata !13, metadata !DIExpression()), !dbg !15
+ %call.i = tail call i32 @_Z6foobarv()
+ call void @llvm.dbg.value(metadata i32 undef, metadata !13, metadata !DIExpression()), !dbg !15
+ %tobool.not.i = icmp eq i32 %a, 0
+ br i1 %tobool.not.i, label %_Z3bari.exit, label %label.i
+
+label.i: ; preds = %entry, %label.i
+ call void @llvm.dbg.label(metadata !14), !dbg !18
+ br label %label.i
+
+_Z3bari.exit: ; preds = %entry
+ %add.i = add nsw i32 %call.i, 10
+ call void @llvm.dbg.value(metadata i32 %add.i, metadata !13, metadata !DIExpression()), !dbg !15
+ ret i32 %add.i
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata) #2
+declare dso_local i32 @_Z6foobarv() local_unnamed_addr #1
+declare void @llvm.dbg.label(metadata) #2
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 12.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "f.cpp", directory: "")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 12.0.0"}
+!7 = distinct !DISubprogram(name: "bar", linkageName: "_Z3bari", scope: !1, file: !1, line: 3, type: !8, scopeLine: 3, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !10}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !{!12, !13, !14}
+!12 = !DILocalVariable(name: "a", arg: 1, scope: !7, file: !1, line: 3, type: !10)
+!13 = !DILocalVariable(name: "b", scope: !7, file: !1, line: 4, type: !10)
+!14 = !DILabel(scope: !7, name: "label", file: !1, line: 6)
+!15 = !DILocation(line: 0, scope: !7)
+!18 = !DILocation(line: 6, column: 1, scope: !7)
More information about the llvm-branch-commits
mailing list