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When compiling with dwarf info, the mfix4300 flag introduced in https://reviews.llvm.org/D116238 can miss some occurrences of the vr4300 mulmul bug if a debug instruction happens to be between two muls.
This revision skips debug instructions in order to fix the mulmul bug detection.
Fixes https://github.com/llvm/llvm-project/issues/53094
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D117615
Files:
llvm/lib/Target/Mips/MipsMulMulBugPass.cpp
llvm/test/CodeGen/Mips/vr4300-mulmul.ll
Index: llvm/test/CodeGen/Mips/vr4300-mulmul.ll
===================================================================
--- llvm/test/CodeGen/Mips/vr4300-mulmul.ll
+++ llvm/test/CodeGen/Mips/vr4300-mulmul.ll
@@ -1,13 +1,14 @@
; RUN: llc -march=mips -mfix4300 -verify-machineinstrs < %s | FileCheck %s
; Function Attrs: mustprogress nofree norecurse nosync nounwind readnone willreturn
-define dso_local float @fun_s(float %x) local_unnamed_addr #0 {
+define dso_local float @fun_s(float %x) local_unnamed_addr !dbg !7 {
entry:
; CHECK-LABEL: fun_s
; CHECK: mul.s
+; CHECK-NEXT: #DEBUG_VALUE: i <- 1
; CHECK-NEXT: nop
-; CHECK: mul.s
%mul = fmul float %x, %x
+ call void @llvm.dbg.value(metadata i32 1, metadata !13, metadata !DIExpression()), !dbg !17
%mul1 = fmul float %mul, %x
ret float %mul1
}
@@ -22,3 +23,23 @@
%mul1 = fmul double %mul, %x
ret double %mul1
}
+
+
+; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "vr4300-mulmul.ll", directory: "/")
+!2 = !{i32 7, !"Dwarf Version", i32 4}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!7 = distinct !DISubprogram(name: "fun_s", linkageName: "fun_s", scope: !1, file: !1, line: 1, type: !8, scopeLine: 2, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !10}
+!10 = !DIBasicType(name: "float", size: 32, encoding: DW_ATE_float)
+!13 = !DILocalVariable(name: "i", scope: !14, file: !1, line: 3, type: !15)
+!14 = distinct !DILexicalBlock(scope: !7, file: !1, line: 3, column: 5)
+!15 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!17 = !DILocation(line: 0, scope: !14)
\ No newline at end of file
Index: llvm/lib/Target/Mips/MipsMulMulBugPass.cpp
===================================================================
--- llvm/lib/Target/Mips/MipsMulMulBugPass.cpp
+++ llvm/lib/Target/Mips/MipsMulMulBugPass.cpp
@@ -110,17 +110,19 @@
const MipsInstrInfo &MipsII) {
bool Modified = false;
+ MachineBasicBlock::instr_iterator NextMII;
+
// Iterate through the instructions in the basic block
for (MachineBasicBlock::instr_iterator MII = MBB.instr_begin(),
E = MBB.instr_end();
- MII != E; ++MII) {
+ MII != E; MII = NextMII) {
- MachineBasicBlock::instr_iterator NextMII = std::next(MII);
+ NextMII = skipDebugInstructionsForward(std::next(MII), E);
// Trigger when the current instruction is a mul and the next instruction
// is either a mul or a branch in case the branch target start with a mul
if (NextMII != E && isFirstMul(*MII) && isSecondMulOrBranch(*NextMII)) {
- LLVM_DEBUG(dbgs() << "Found mulmul!");
+ LLVM_DEBUG(dbgs() << "Found mulmul!\n");
const MCInstrDesc &NewMCID = MipsII.get(Mips::NOP);
BuildMI(MBB, NextMII, DebugLoc(), NewMCID);
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