[PATCH] D157253: [ValueTracking] Dereferenceable and !NullPointerIsDefined imply non-zero
luxufan via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Sun Aug 13 20:58:41 PDT 2023
This revision was automatically updated to reflect the committed changes.
Closed by commit rG43114cb696c0: [ValueTracking] Dereferenceable and !NullPointerIsDefined imply non-zero (authored by StephenFan).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D157253/new/
https://reviews.llvm.org/D157253
Files:
llvm/lib/Analysis/ValueTracking.cpp
llvm/test/Transforms/InstSimplify/icmp.ll
Index: llvm/test/Transforms/InstSimplify/icmp.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/icmp.ll
+++ llvm/test/Transforms/InstSimplify/icmp.ll
@@ -258,3 +258,23 @@
%cmp = icmp ne i8 %sub, %x
ret i1 %cmp
}
+
+define i1 @load_ptr(ptr %p) {
+; CHECK-LABEL: @load_ptr(
+; CHECK-NEXT: ret i1 true
+;
+ %load_p = load ptr, ptr %p, !dereferenceable !{i64 8}
+ %r = icmp ne ptr %load_p, null
+ ret i1 %r
+}
+
+define i1 @load_ptr_null_valid(ptr %p) null_pointer_is_valid {
+; CHECK-LABEL: @load_ptr_null_valid(
+; CHECK-NEXT: [[LOAD_P:%.*]] = load ptr, ptr [[P:%.*]], align 8, !dereferenceable !0
+; CHECK-NEXT: [[R:%.*]] = icmp ne ptr [[LOAD_P]], null
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %load_p = load ptr, ptr %p, !dereferenceable !{i64 8}
+ %r = icmp ne ptr %load_p, null
+ ret i1 %r
+}
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -2707,14 +2707,20 @@
return isKnownNonZero(I->getOperand(0), Depth, Q) &&
isGuaranteedNotToBePoison(I->getOperand(0), Q.AC, Q.CxtI, Q.DT,
Depth);
- case Instruction::Load:
- // A Load tagged with nonnull metadata is never null.
- if (Q.IIQ.getMetadata(cast<LoadInst>(I), LLVMContext::MD_nonnull))
- return true;
+ case Instruction::Load: {
+ auto *LI = cast<LoadInst>(I);
+ // A Load tagged with nonnull or dereferenceable with null pointer undefined
+ // is never null.
+ if (auto *PtrT = dyn_cast<PointerType>(I->getType()))
+ if (Q.IIQ.getMetadata(LI, LLVMContext::MD_nonnull) ||
+ (Q.IIQ.getMetadata(LI, LLVMContext::MD_dereferenceable) &&
+ !NullPointerIsDefined(LI->getFunction(), PtrT->getAddressSpace())))
+ return true;
// No need to fall through to computeKnownBits as range metadata is already
// handled in isKnownNonZero.
return false;
+ }
case Instruction::Call:
case Instruction::Invoke:
if (I->getType()->isPointerTy()) {
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