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[DebugInfo][GVN] Propagate DebugLoc from load-of-select to select (#114233)

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When replacing a load from a selected pointer with a select of the known
stored values, we currently assign no DebugLoc to the select; this patch
propagates the load's DebugLoc to the new select, since it is a direct
replacement.
This commit is contained in:
Stephen Tozer 2024-11-15 17:07:33 +00:00 committed by GitHub
parent 31ee667eb0
commit f37bc8cfbf
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2 changed files with 58 additions and 0 deletions
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3
llvm/lib/Transforms/Scalar/GVN.cpp
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@ -1129,6 +1129,9 @@ Value *AvailableValue::MaterializeAdjustedValue(LoadInst *Load,
assert(V1 && V2 && "both value operands of the select must be present");
Res =
SelectInst::Create(Sel->getCondition(), V1, V2, "", Sel->getIterator());
// We use the DebugLoc from the original load here, as this instruction
// materializes the value that would previously have been loaded.
cast<SelectInst>(Res)->setDebugLoc(Load->getDebugLoc());
} else {
llvm_unreachable("Should not materialize value from dead block");
}

55
llvm/test/Transforms/GVN/debugloc-load-select.ll Normal file
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@ -0,0 +1,55 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt < %s -p=gvn -S | FileCheck %s
;; Check that when GVN replaces a load of a select with a select of the values
;; that would be loaded, we propagate the debug location from the load to the
;; select, since the select is a replacement that produces the same value.
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
define void @loadtree(ptr %topol, i1 %cmp168) {
; CHECK-LABEL: define void @loadtree(
; CHECK-SAME: ptr [[TOPOL:%.*]], i1 [[CMP168:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr null, align 4
; CHECK-NEXT: [[TMP1:%.*]] = load i32, ptr [[TOPOL]], align 4
; CHECK-NEXT: [[CMP1681:%.*]] = icmp sgt i32 [[TMP0]], [[TMP1]]
; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[CMP168]], i32 [[TMP1]], i32 [[TMP0]], !dbg [[DBG3:![0-9]+]]
; CHECK-NEXT: [[DOT:%.*]] = select i1 [[CMP168]], ptr [[TOPOL]], ptr null, !dbg [[DBG9:![0-9]+]]
; CHECK-NEXT: [[CMP174_NOT473:%.*]] = icmp eq i32 [[TMP2]], 0
; CHECK-NEXT: ret void
;
entry:
%0 = load i32, ptr null, align 4
%1 = load i32, ptr %topol, align 4
%cmp1681 = icmp sgt i32 %0, %1
%. = select i1 %cmp168, ptr %topol, ptr null, !dbg !9
%2 = load i32, ptr %., align 4, !dbg !3
%cmp174.not473 = icmp eq i32 %2, 0
ret void
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!2}
!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 20.0.0git")
!1 = !DIFile(filename: "/tmp/mltaln9.c", directory: "/tmp")
!2 = !{i32 2, !"Debug Info Version", i32 3}
!3 = !DILocation(line: 4, column: 22, scope: !5)
!4 = !DIFile(filename: "mltaln9.c", directory: "/tmp")
!5 = distinct !DISubprogram(name: "loadtree", scope: !4, file: !4, line: 869, type: !6, scopeLine: 870, unit: !0, retainedNodes: !8)
!6 = distinct !DISubroutineType(types: !7)
!7 = !{null}
!8 = !{}
!9 = !DILocation(line: 9, column: 22, scope: !5)
;.
; CHECK: [[META0:![0-9]+]] = distinct !DICompileUnit(language: DW_LANG_C11, file: [[META1:![0-9]+]], producer: "{{.*}}clang version {{.*}}", isOptimized: false, runtimeVersion: 0, emissionKind: NoDebug)
; CHECK: [[META1]] = !DIFile(filename: "/tmp/mltaln9.c", directory: {{.*}})
; CHECK: [[DBG3]] = !DILocation(line: 4, column: 22, scope: [[META4:![0-9]+]])
; CHECK: [[META4]] = distinct !DISubprogram(name: "loadtree", scope: [[META5:![0-9]+]], file: [[META5]], line: 869, type: [[META6:![0-9]+]], scopeLine: 870, spFlags: DISPFlagDefinition, unit: [[META0]], retainedNodes: [[META8:![0-9]+]])
; CHECK: [[META5]] = !DIFile(filename: "mltaln9.c", directory: {{.*}})
; CHECK: [[META6]] = distinct !DISubroutineType(types: [[META7:![0-9]+]])
; CHECK: [[META7]] = !{null}
; CHECK: [[META8]] = !{}
; CHECK: [[DBG9]] = !DILocation(line: 9, column: 22, scope: [[META4]])
;.