[llvm] e890821 - [LSR] Support SCEVPtrToAddr in SCEVDbgValueBuilder.

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2026-02-07T14:02:45Z
New Revision: e8908215de669f3d879f6e2265fa796d93a9872b

URL: https://github.com/llvm/llvm-project/commit/e8908215de669f3d879f6e2265fa796d93a9872b
DIFF: https://github.com/llvm/llvm-project/commit/e8908215de669f3d879f6e2265fa796d93a9872b.diff

LOG: [LSR] Support SCEVPtrToAddr in SCEVDbgValueBuilder.

Allow SCEVPtrToAddr as cast in assertion in SCEVDbgValueBuilder.
SCEVPtrToAddr is handled similarly to SCEVPtrToInt.

Fixes a crash with debug info after bd40d1de9c9ee, which started to
generate ptrtoaddr instead of ptrtoint expressions.

Added: 
    llvm/test/Transforms/LoopStrengthReduce/X86/debuginfo-scev-salvage-ptrtoaddr.ll

Modified: 
    llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index e9d78baece25b..839942fac6716 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -6488,7 +6488,8 @@ struct SCEVDbgValueBuilder {
     } else if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(S)) {
       // Assert if a new and unknown SCEVCastEXpr type is encountered.
       assert((isa<SCEVZeroExtendExpr>(Cast) || isa<SCEVTruncateExpr>(Cast) ||
-              isa<SCEVPtrToIntExpr>(Cast) || isa<SCEVSignExtendExpr>(Cast)) &&
+              isa<SCEVPtrToIntExpr>(Cast) || isa<SCEVPtrToAddrExpr>(Cast) ||
+              isa<SCEVSignExtendExpr>(Cast)) &&
              "Unexpected cast type in SCEV.");
       Success &= pushCast(Cast, (isa<SCEVSignExtendExpr>(Cast)));
 

diff  --git a/llvm/test/Transforms/LoopStrengthReduce/X86/debuginfo-scev-salvage-ptrtoaddr.ll b/llvm/test/Transforms/LoopStrengthReduce/X86/debuginfo-scev-salvage-ptrtoaddr.ll
new file mode 100644
index 0000000000000..3cbe40ad0f2ef
--- /dev/null
+++ b/llvm/test/Transforms/LoopStrengthReduce/X86/debuginfo-scev-salvage-ptrtoaddr.ll
@@ -0,0 +1,61 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: opt -S -loop-reduce %s -o - | FileCheck %s
+
+;; Ensure that debug value salvaging does not crash when encountering
+;; SCEVPtrToAddrExpr in the SCEV expression tree.
+
+
+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 i64 @test(ptr %p) {
+; CHECK-LABEL: define i64 @test(
+; CHECK-SAME: ptr [[P:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[P1:%.*]] = ptrtoaddr ptr [[P]] to i64
+; CHECK-NEXT:    [[TMP0:%.*]] = add i64 [[P1]], -1
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[LSR_IV:%.*]] = phi i64 [ [[LSR_IV_NEXT:%.*]], %[[LOOP]] ], [ [[TMP0]], %[[ENTRY]] ]
+; CHECK-NEXT:      #dbg_value(i64 [[LSR_IV]], [[META4:![0-9]+]], !DIExpression(DW_OP_plus_uconst, 1, DW_OP_stack_value), [[META8:![0-9]+]])
+; CHECK-NEXT:    [[LSR_IV_NEXT]] = add i64 [[LSR_IV]], 1
+; CHECK-NEXT:    br i1 false, label %[[EXIT:.*]], label %[[LOOP]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret i64 [[LSR_IV_NEXT]]
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi ptr [ %p, %entry ], [ %iv.next, %loop ]
+  %addr = ptrtoaddr ptr %iv to i64
+    #dbg_value(i64 %addr, !4, !DIExpression(), !9)
+  %iv.next = getelementptr i8, ptr %iv, i64 1
+  br i1 false, label %exit, label %loop
+
+exit:
+  ret i64 %addr
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, retainedTypes: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp")
+!2 = !{}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !DILocalVariable(name: "addr", scope: !5, file: !1, line: 2, type: !7)
+!5 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 1, type: !6, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!6 = !DISubroutineType(types: !2)
+!7 = !DIBasicType(name: "long", size: 64, encoding: DW_ATE_signed)
+!9 = !DILocation(line: 2, scope: !5)
+;.
+; CHECK: [[META0:![0-9]+]] = distinct !DICompileUnit(language: DW_LANG_C11, file: [[META1:![0-9]+]], producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, retainedTypes: [[META2:![0-9]+]], splitDebugInlining: false, nameTableKind: None)
+; CHECK: [[META1]] = !DIFile(filename: "{{.*}}test.c", directory: {{.*}})
+; CHECK: [[META2]] = !{}
+; CHECK: [[META4]] = !DILocalVariable(name: "addr", scope: [[META5:![0-9]+]], file: [[META1]], line: 2, type: [[META7:![0-9]+]])
+; CHECK: [[META5]] = distinct !DISubprogram(name: "test", scope: [[META1]], file: [[META1]], line: 1, type: [[META6:![0-9]+]], scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: [[META0]], retainedNodes: [[META2]])
+; CHECK: [[META6]] = !DISubroutineType(types: [[META2]])
+; CHECK: [[META7]] = !DIBasicType(name: "long", size: 64, encoding: DW_ATE_signed)
+; CHECK: [[META8]] = !DILocation(line: 2, scope: [[META5]])
+;.