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Add debug location to strlen in LoopIdiomRecognize pass #140164

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Merged
merged 4 commits into from
May 16, 2025
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Merged

Add debug location to strlen in LoopIdiomRecognize pass #140164

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35fb19b
Add debug location to strlen in LoopIdiomRecognize pass
amykhuang May 14, 2025
276b552
Set debug loc on the IRBuilder instead of instruction
amykhuang May 16, 2025
d2e863e
Edit test case debug info
amykhuang May 16, 2025
6a672ac
Change debug location matching to a variable
amykhuang May 16, 2025
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1 change: 1 addition & 0 deletions llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1764,6 +1764,7 @@ bool LoopIdiomRecognize::recognizeAndInsertStrLen() {
}

IRBuilder<> Builder(Preheader->getTerminator());
Builder.SetCurrentDebugLocation(CurLoop->getStartLoc());
SCEVExpander Expander(*SE, Preheader->getModule()->getDataLayout(),
"strlen_idiom");
Value *MaterialzedBase = Expander.expandCodeFor(
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52 changes: 52 additions & 0 deletions llvm/test/Transforms/LoopIdiom/strlen.ll
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Expand Up @@ -612,3 +612,55 @@ while.end:
ret i64 %sub.ptr.sub
}

define i64 @valid_basic_strlen_with_dbg(ptr %str) {
; Make sure that the call to strlen has debug info attached.
; CHECK-LABEL: define i64 @valid_basic_strlen_with_dbg(
; CHECK-SAME: ptr [[STR:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*]]:
; CHECK-NEXT: [[STRLEN:%.*]] = call i64 @strlen(ptr [[STR]]), !dbg [[DBGLOC1:![0-9]+]]
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr i8, ptr [[STR]], i64 [[STRLEN]]
; CHECK-NEXT: br label %[[WHILE_COND:.*]]
; CHECK: [[WHILE_COND]]:
; CHECK-NEXT: [[STR_ADDR_0:%.*]] = phi ptr [ [[STR]], %[[ENTRY]] ], [ [[INCDEC_PTR:%.*]], %[[WHILE_COND]] ]
; CHECK-NEXT: [[TMP0:%.*]] = load i8, ptr [[STR_ADDR_0]], align 1, !dbg [[DBGLOC2:![0-9]+]]
; CHECK-NEXT: [[CMP_NOT:%.*]] = icmp eq i8 [[TMP0]], 0, !dbg [[DBGLOC2]]
; CHECK-NEXT: [[INCDEC_PTR]] = getelementptr i8, ptr [[STR_ADDR_0]], i64 1, !dbg [[DBGLOC2]]
; CHECK-NEXT: br i1 true, label %[[WHILE_END:.*]], label %[[WHILE_COND]], !dbg [[DBGLOC1]]
; CHECK: [[WHILE_END]]:
; CHECK-NEXT: [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[SCEVGEP]] to i64, !dbg [[DBGLOC2]]
; CHECK-NEXT: [[SUB_PTR_RHS_CAST:%.*]] = ptrtoint ptr [[STR]] to i64, !dbg [[DBGLOC2]]
; CHECK-NEXT: [[SUB_PTR_SUB:%.*]] = sub i64 [[SUB_PTR_LHS_CAST]], [[SUB_PTR_RHS_CAST]], !dbg [[DBGLOC2]]
; CHECK-NEXT: ret i64 [[SUB_PTR_SUB]], !dbg [[DBGLOC2]]
;
; CHECK: [[DBGLOC1]] = !DILocation(line: 3, column: 3
; CHECK: [[DBGLOC2]] = !DILocation(line: 5, column: 3
;
entry:
br label %while.cond

while.cond:
%str.addr.0 = phi ptr [ %str, %entry ], [ %incdec.ptr, %while.cond ]
%0 = load i8, ptr %str.addr.0, align 1, !dbg !8
%cmp.not = icmp eq i8 %0, 0, !dbg !8
%incdec.ptr = getelementptr i8, ptr %str.addr.0, i64 1, !dbg !8
br i1 %cmp.not, label %while.end, label %while.cond, !dbg !4

while.end:
%sub.ptr.lhs.cast = ptrtoint ptr %str.addr.0 to i64, !dbg !8
%sub.ptr.rhs.cast = ptrtoint ptr %str to i64, !dbg !8
%sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast, !dbg !8
ret i64 %sub.ptr.sub, !dbg !8
}

!llvm.module.flags = !{!0}
!llvm.dbg.cu = !{!1}

!0 = !{i32 1, !"Debug Info Version", i32 3}
!1 = distinct !DICompileUnit(language: DW_LANG_C99, file: !2, producer: "clang version 2.9 (trunk 127165:127174)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !3, retainedTypes: !3)
!2 = !DIFile(filename: "strlen.c", directory: "/tmp")
!3 = !{}
!4 = !DILocation(line: 3, column: 3, scope: !5)
!5 = distinct !DILexicalBlock(scope: !6, file: !2, line: 2, column: 21)
!6 = distinct !DISubprogram(name: "foo", scope: !2, file: !2, line: 2, type: !7, virtualIndex: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !1)
!7 = !DISubroutineType(types: !3)
!8 = !DILocation(line: 5, column: 3, scope: !5)
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