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[KeyInstr] Don't propagate source atoms to new uncond br in splitBasicBlock (#139070)

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splitBasicBlock inserts an unconditional branch in the "before" block to
the "after" block. It copies the DebugLoc from the split point. Prevent
it copying the source location atom.

Add unittest.

RFC:
https://discourse.llvm.org/t/rfc-improving-is-stmt-placement-for-better-interactive-debugging/82668
This commit is contained in:
Orlando Cazalet-Hyams 2025-05-08 14:26:37 +01:00 committed by GitHub
parent e9df48e8a4
commit d2fe889676
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GPG Key ID: B5690EEEBB952194
2 changed files with 71 additions and 2 deletions
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4
llvm/lib/IR/BasicBlock.cpp
View File

@ -612,7 +612,7 @@ BasicBlock *BasicBlock::splitBasicBlock(iterator I, const Twine &BBName,
this->getNextNode());
// Save DebugLoc of split point before invalidating iterator.
DebugLoc Loc = I->getStableDebugLoc();
DebugLoc Loc = I->getStableDebugLoc()->getWithoutAtom();
// Move all of the specified instructions from the original basic block into
// the new basic block.
New->splice(New->end(), this, I, end());
@ -641,7 +641,7 @@ BasicBlock *BasicBlock::splitBasicBlockBefore(iterator I, const Twine &BBName) {
BasicBlock *New = BasicBlock::Create(getContext(), BBName, getParent(), this);
// Save DebugLoc of split point before invalidating iterator.
DebugLoc Loc = I->getDebugLoc();
DebugLoc Loc = I->getDebugLoc()->getWithoutAtom();
// Move all of the specified instructions from the original basic block into
// the new basic block.
New->splice(New->end(), this, begin(), I);

69
llvm/unittests/IR/BasicBlockDbgInfoTest.cpp
View File

@ -149,6 +149,75 @@ TEST(BasicBlockDbgInfoTest, SplitBasicBlockBefore) {
ASSERT_TRUE(I2->hasDbgRecords());
}
TEST(BasicBlockDbgInfoTest, DropSourceAtomOnSplit) {
LLVMContext C;
std::unique_ptr<Module> M = parseIR(C, R"---(
define dso_local void @func() !dbg !10 {
%1 = alloca i32, align 4
ret void, !dbg !DILocation(line: 3, column: 2, scope: !10, atomGroup: 1, atomRank: 1)
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!2, !3}
!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "dummy", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
!1 = !DIFile(filename: "dummy", directory: "dummy")
!2 = !{i32 7, !"Dwarf Version", i32 5}
!3 = !{i32 2, !"Debug Info Version", i32 3}
!10 = distinct !DISubprogram(name: "func", scope: !1, file: !1, line: 1, type: !11, scopeLine: 1, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !13)
!11 = !DISubroutineType(types: !12)
!12 = !{null}
!13 = !{}
!14 = !DILocalVariable(name: "a", scope: !10, file: !1, line: 2, type: !15)
!15 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
)---");
ASSERT_TRUE(M);
Function *F = M->getFunction("func");
// Test splitBasicBlockBefore.
{
BasicBlock &BB = F->back();
// Split at `ret void`.
BasicBlock *Before =
BB.splitBasicBlockBefore(std::prev(BB.end(), 1), "before");
const DebugLoc &BrToAfterDL = Before->getTerminator()->getDebugLoc();
ASSERT_TRUE(BrToAfterDL);
EXPECT_EQ(BrToAfterDL->getAtomGroup(), 0u);
BasicBlock *After = Before->getSingleSuccessor();
ASSERT_TRUE(After);
const DebugLoc &OrigTerminatorDL = After->getTerminator()->getDebugLoc();
ASSERT_TRUE(OrigTerminatorDL);
#ifdef EXPERIMENTAL_KEY_INSTRUCTIONS
EXPECT_EQ(OrigTerminatorDL->getAtomGroup(), 1u);
#else
EXPECT_EQ(OrigTerminatorDL->getAtomGroup(), 0u);
#endif
}
// Test splitBasicBlock.
{
BasicBlock &BB = F->back();
// Split at `ret void`.
BasicBlock *After = BB.splitBasicBlock(std::prev(BB.end(), 1), "before");
const DebugLoc &OrigTerminatorDL = After->getTerminator()->getDebugLoc();
ASSERT_TRUE(OrigTerminatorDL);
#ifdef EXPERIMENTAL_KEY_INSTRUCTIONS
EXPECT_EQ(OrigTerminatorDL->getAtomGroup(), 1u);
#else
EXPECT_EQ(OrigTerminatorDL->getAtomGroup(), 0u);
#endif
BasicBlock *Before = After->getSinglePredecessor();
ASSERT_TRUE(Before);
const DebugLoc &BrToAfterDL = Before->getTerminator()->getDebugLoc();
ASSERT_TRUE(BrToAfterDL);
EXPECT_EQ(BrToAfterDL->getAtomGroup(), 0u);
}
}
TEST(BasicBlockDbgInfoTest, MarkerOperations) {
LLVMContext C;
std::unique_ptr<Module> M = parseIR(C, R"(