[llvm] bf7aaf7 - [ValueTracking] Handle idx widths > 64 bit in GetPointerBaseWithConst. (#221692)

[via llvm-commits]

Author: Florian Hahn
Date: 2026-09-07T12:15:40+01:00
New Revision: bf7aaf77d0916adaa3cd043fc0966a33c1364e2c

URL: https://github.com/llvm/llvm-project/commit/bf7aaf77d0916adaa3cd043fc0966a33c1364e2c
DIFF: https://github.com/llvm/llvm-project/commit/bf7aaf77d0916adaa3cd043fc0966a33c1364e2c.diff

LOG: [ValueTracking] Handle idx widths > 64 bit in GetPointerBaseWithConst. (#221692)

GetPointerBaseWithConstantOffset may be called for GEPs with indices
that do not fit into 64 bit. Use trySExtValue to avoid assertions in the
newly added tests.

PR: https://github.com/llvm/llvm-project/pull/221692

Added: 
    llvm/test/Transforms/DeadStoreElimination/wide-pointer-index-offset.ll

Modified: 
    llvm/include/llvm/Analysis/ValueTracking.h

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Analysis/ValueTracking.h b/llvm/include/llvm/Analysis/ValueTracking.h
index 87dc4e713929c5..9a1fdd0ca05a95 100644
--- a/llvm/include/llvm/Analysis/ValueTracking.h
+++ b/llvm/include/llvm/Analysis/ValueTracking.h
@@ -25,6 +25,7 @@
 #include "llvm/Support/Compiler.h"
 #include <cassert>
 #include <cstdint>
+#include <optional>
 
 namespace llvm {
 
@@ -376,7 +377,13 @@ inline Value *GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
   Value *Base =
       Ptr->stripAndAccumulateConstantOffsets(DL, OffsetAPInt, AllowNonInbounds);
 
-  Offset = OffsetAPInt.getSExtValue();
+  std::optional<int64_t> OffsetInt64 = OffsetAPInt.trySExtValue();
+  if (!OffsetInt64) {
+    Offset = 0;
+    return Ptr;
+  }
+
+  Offset = *OffsetInt64;
   return Base;
 }
 inline const Value *

diff  --git a/llvm/test/Transforms/DeadStoreElimination/wide-pointer-index-offset.ll b/llvm/test/Transforms/DeadStoreElimination/wide-pointer-index-offset.ll
new file mode 100644
index 00000000000000..12b9e4f1487493
--- /dev/null
+++ b/llvm/test/Transforms/DeadStoreElimination/wide-pointer-index-offset.ll
@@ -0,0 +1,34 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: opt -passes=dse -S %s | FileCheck %s
+
+target datalayout = "e-m:e-p:128:128:128"
+
+; Tests with constant offsets that does not fit into i64.
+
+define void @wide_offset_store_not_eliminated(ptr %A) {
+; CHECK-LABEL: define void @wide_offset_store_not_eliminated(
+; CHECK-SAME: ptr [[A:%.*]]) {
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i8, ptr [[A]], i128 147573952589676412928
+; CHECK-NEXT:    store i32 1, ptr [[GEP]], align 4
+; CHECK-NEXT:    store i32 2, ptr [[A]], align 4
+; CHECK-NEXT:    ret void
+;
+  %gep = getelementptr i8, ptr %A, i128 147573952589676412928
+  store i32 1, ptr %gep, align 4
+  store i32 2, ptr %A, align 4
+  ret void
+}
+
+define void @wide_offset_load_store(ptr %A) {
+; CHECK-LABEL: define void @wide_offset_load_store(
+; CHECK-SAME: ptr [[A:%.*]]) {
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i8, ptr [[A]], i128 147573952589676412928
+; CHECK-NEXT:    [[L:%.*]] = load i32, ptr [[GEP]], align 4
+; CHECK-NEXT:    store i32 [[L]], ptr [[A]], align 4
+; CHECK-NEXT:    ret void
+;
+  %gep = getelementptr i8, ptr %A, i128 147573952589676412928
+  %l = load i32, ptr %gep, align 4
+  store i32 %l, ptr %A, align 4
+  ret void
+}