[llvm] [Value] Look through inttoptr (add ..) in accumulateConstantOffsets (PR #124981)
via llvm-commits
llvm-commits at lists.llvm.org
Wed Jan 29 12:33:21 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: Florian Hahn (fhahn)
<details>
<summary>Changes</summary>
Look through inttoptr (add (ptrtoint P), C) when accumulating offsets.
Adds a missing fold after
https://github.com/llvm/llvm-project/pull/123518
Alive2 for the tests with changes: https://alive2.llvm.org/ce/z/VvPrzv
---
Full diff: https://github.com/llvm/llvm-project/pull/124981.diff
3 Files Affected:
- (modified) llvm/lib/Analysis/ConstantFolding.cpp (+5-4)
- (modified) llvm/lib/IR/Value.cpp (+19)
- (added) llvm/test/Transforms/InstSimplify/constant-fold-inttoptr-add.ll (+84)
``````````diff
diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index 80c1277e631653..04741c57492ae6 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -1258,11 +1258,12 @@ Constant *llvm::ConstantFoldCompareInstOperands(
if (Ops0->getType()->isPointerTy() && !ICmpInst::isSigned(Predicate)) {
unsigned IndexWidth = DL.getIndexTypeSizeInBits(Ops0->getType());
APInt Offset0(IndexWidth, 0);
- Value *Stripped0 =
- Ops0->stripAndAccumulateInBoundsConstantOffsets(DL, Offset0);
+ bool AllowNonInbounds = ICmpInst::isEquality(Predicate);
+ Value *Stripped0 = Ops0->stripAndAccumulateConstantOffsets(
+ DL, Offset0, AllowNonInbounds);
APInt Offset1(IndexWidth, 0);
- Value *Stripped1 =
- Ops1->stripAndAccumulateInBoundsConstantOffsets(DL, Offset1);
+ Value *Stripped1 = Ops1->stripAndAccumulateConstantOffsets(
+ DL, Offset1, AllowNonInbounds);
if (Stripped0 == Stripped1)
return ConstantInt::getBool(
Ops0->getContext(),
diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index eddb67282fca46..48905609429b19 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -775,6 +775,25 @@ const Value *Value::stripAndAccumulateConstantOffsets(
V = RV;
if (AllowInvariantGroup && Call->isLaunderOrStripInvariantGroup())
V = Call->getArgOperand(0);
+ } else if (auto *Int2Ptr = dyn_cast<Operator>(V)) {
+ // Try to accumulate across (inttoptr (add (ptrtoint p), off)).
+ if (!Int2Ptr || Int2Ptr->getOpcode() != Instruction::IntToPtr ||
+ Int2Ptr->getOperand(0)->getType()->getScalarSizeInBits() != BitWidth)
+ return V;
+ auto *Add = dyn_cast<AddOperator>(Int2Ptr->getOperand(0));
+ if (!AllowNonInbounds || !Add)
+ return V;
+ auto *Ptr2Int = dyn_cast<PtrToIntOperator>(Add->getOperand(0));
+ auto *CI = dyn_cast<ConstantInt>(Add->getOperand(1));
+ if (!Ptr2Int || !CI)
+ return V;
+
+ APInt AddOffset = CI->getValue();
+ if (AddOffset.getSignificantBits() > BitWidth)
+ return V;
+
+ Offset = AddOffset.sextOrTrunc(BitWidth);
+ V = Ptr2Int->getOperand(0);
}
assert(V->getType()->isPtrOrPtrVectorTy() && "Unexpected operand type!");
} while (Visited.insert(V).second);
diff --git a/llvm/test/Transforms/InstSimplify/constant-fold-inttoptr-add.ll b/llvm/test/Transforms/InstSimplify/constant-fold-inttoptr-add.ll
new file mode 100644
index 00000000000000..a0a34e2fe73958
--- /dev/null
+++ b/llvm/test/Transforms/InstSimplify/constant-fold-inttoptr-add.ll
@@ -0,0 +1,84 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -p instcombine -S %s | FileCheck %s
+
+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"
+
+ at glob = external global [314 x i64]
+
+define i1 @known_constexpr_add_eq() {
+; CHECK-LABEL: define i1 @known_constexpr_add_eq() {
+; CHECK-NEXT: ret i1 false
+;
+ %cond = icmp eq ptr getelementptr inbounds nuw (i8, ptr @glob, i64 80), inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr)
+ ret i1 %cond
+}
+
+define i1 @known_constexpr_add_ne() {
+; CHECK-LABEL: define i1 @known_constexpr_add_ne() {
+; CHECK-NEXT: ret i1 true
+;
+ %cond = icmp ne ptr getelementptr inbounds nuw (i8, ptr @glob, i64 80), inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr)
+ ret i1 %cond
+}
+
+define i1 @wrap_positive_to_negate() {
+; CHECK-LABEL: define i1 @wrap_positive_to_negate() {
+; CHECK-NEXT: ret i1 false
+;
+ %cond = icmp eq ptr @glob, inttoptr (i64 add (i64 ptrtoint (ptr getelementptr nuw (i8, ptr @glob, i64 1)to i64), i64 9223372036854775808) to ptr)
+ ret i1 %cond
+}
+
+; 9223372036854775808 = 2^63
+define i1 @wrap_positive_to_zero() {
+; CHECK-LABEL: define i1 @wrap_positive_to_zero() {
+; CHECK-NEXT: ret i1 true
+;
+ %cond = icmp eq ptr @glob, inttoptr (i64 add (i64 ptrtoint (ptr getelementptr nuw (i8, ptr @glob, i64 9223372036854775808)to i64), i64 9223372036854775808) to ptr)
+ ret i1 %cond
+}
+
+define i1 @not_known_constexpr_add_sle() {
+; CHECK-LABEL: define i1 @not_known_constexpr_add_sle() {
+; CHECK-NEXT: [[COND:%.*]] = icmp sle ptr @glob, inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr)
+; CHECK-NEXT: ret i1 [[COND]]
+;
+ %cond = icmp sle ptr @glob, inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr)
+ ret i1 %cond
+}
+
+define i1 @not_known_constexpr_add_ule() {
+; CHECK-LABEL: define i1 @not_known_constexpr_add_ule() {
+; CHECK-NEXT: [[COND:%.*]] = icmp ule ptr @glob, inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr)
+; CHECK-NEXT: ret i1 [[COND]]
+;
+ %cond = icmp ule ptr @glob, inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr)
+ ret i1 %cond
+}
+
+define i1 @not_known_constexpr_add_sge() {
+; CHECK-LABEL: define i1 @not_known_constexpr_add_sge() {
+; CHECK-NEXT: [[COND:%.*]] = icmp sge ptr @glob, inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr)
+; CHECK-NEXT: ret i1 [[COND]]
+;
+ %cond = icmp sge ptr @glob, inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr)
+ ret i1 %cond
+}
+
+define i1 @not_known_constexpr_add_uge() {
+; CHECK-LABEL: define i1 @not_known_constexpr_add_uge() {
+; CHECK-NEXT: [[COND:%.*]] = icmp uge ptr @glob, inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr)
+; CHECK-NEXT: ret i1 [[COND]]
+;
+ %cond = icmp uge ptr @glob, inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr)
+ ret i1 %cond
+}
+
+define i1 @not_known_integer_width_does_not_match_pointer_index_width() {
+; CHECK-LABEL: define i1 @not_known_integer_width_does_not_match_pointer_index_width() {
+; CHECK-NEXT: [[COND:%.*]] = icmp eq ptr getelementptr inbounds nuw (i8, ptr @glob, i64 80), inttoptr (i32 add (i32 ptrtoint (ptr @glob to i32), i32 -80) to ptr)
+; CHECK-NEXT: ret i1 [[COND]]
+;
+ %cond = icmp eq ptr getelementptr inbounds nuw (i8, ptr @glob, i64 80), inttoptr (i32 add (i32 ptrtoint (ptr @glob to i32), i32 -80) to ptr)
+ ret i1 %cond
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/124981
More information about the llvm-commits
mailing list