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Fix LDV InstrRefBasedImpl to not crash when encountering unreachable MBBs. 

The testcase was delta-reduced from an LTO build with sanitizer
coverage and the MIR tail duplication pass caused a machine basic
block to become unreachable in MIR. This caused the MBB to be invisible
to the reverse post-order traversal used to initialize the MBB <->
RPONumber lookup tables.

rdar://97226240

Differential Revision: https://reviews.llvm.org/D130999
This commit is contained in:
Adrian Prantl 2022-08-02 10:27:45 -07:00
parent c5ccb78ade
commit 905f2d1ecb
2 changed files with 45 additions and 2 deletions
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9
llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
View File

@ -2933,12 +2933,17 @@ void InstrRefBasedLDV::initialSetup(MachineFunction &MF) {
// Compute mappings of block <=> RPO order.
ReversePostOrderTraversal<MachineFunction *> RPOT(&MF);
unsigned int RPONumber = 0;
for (MachineBasicBlock *MBB : RPOT) {
auto processMBB = [&](MachineBasicBlock *MBB) {
OrderToBB[RPONumber] = MBB;
BBToOrder[MBB] = RPONumber;
BBNumToRPO[MBB->getNumber()] = RPONumber;
++RPONumber;
}
};
for (MachineBasicBlock *MBB : RPOT)
processMBB(MBB);
for (MachineBasicBlock &MBB : MF)
if (BBToOrder.find(&MBB) == BBToOrder.end())
processMBB(&MBB);
// Order value substitutions by their "source" operand pair, for quick lookup.
llvm::sort(MF.DebugValueSubstitutions);

38
llvm/test/DebugInfo/MIR/X86/ldv_unreachable_blocks.mir Normal file
View File

@ -0,0 +1,38 @@
# RUN: llc -mtriple=x86_64-apple-macos %s -start-before=livedebugvalues -filetype=obj -o - | llvm-dwarfdump - | FileCheck %s
# CHECK: DW_TAG_subprogram
# Test that LiveDebugValues can handle MBBs that are not reachable in a RPOT.
--- |
define hidden zeroext i1 @__foo_block_invoke(i8* nocapture noundef readonly %.block_descriptor, i64 noundef %type) !dbg !5 {
entry:
%call2.i = tail call zeroext i8 @foo_len(), !dbg !10
%cmp.i102.i = icmp ult i8 %call2.i, 64, !dbg !10
br i1 %cmp.i102.i, label %bar_length.exit105.i, label %if.else.i103.i, !dbg !10
if.else.i103.i: ; preds = %sw.bb.i
br label %bar_length.exit105.i
bar_length.exit105.i: ; preds = %if.else.i103.i, %sw.bb.i
unreachable
baz_size.exit: ; preds = %bar_length.exit131.i, %bar_length.exit105.i, %bar_length.exit.i.baz_size.exit_crit_edge
unreachable
}
declare zeroext i8 @foo_len() local_unnamed_addr
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !6, producer: "Apple clang", isOptimized: true, flags: "-fsanitize=fuzzer-no-link,address", runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !2, globals: !2, splitDebugInlining: false, nameTableKind: None, sysroot: "/", sdk: "MacOSX.sdk")
!2 = !{}
!3 = !{i32 2, !"Debug Info Version", i32 3}
!4 = !{i32 1, !"LTOPostLink", i32 1}
!5 = distinct !DISubprogram(name: "__foo_block_invoke", linkageName: "__foo_block_invoke", scope: !6, file: !6, line: 557, type: !7, scopeLine: 557, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
!6 = !DIFile(filename: "t.c", directory: "")
!7 = !DISubroutineType(types: !2)
!10 = !DILocation(line: 558, column: 7, scope: !12)
!12 = distinct !DILexicalBlock(scope: !5, file: !6, line: 557, column: 50)
name: __foo_block_invoke
body: |
bb.0.entry:
JCC_1 %bb.1, 5, implicit $eflags, debug-location !10
bb.28.baz_size.exit:
RET64 $al, debug-location !10
bb.1:
successors:
bb.25.if.else.i103.i (address-taken):
JMP_1 %bb.28