Attributor: Don't rely on use_empty for constants

[arsenm]

This allows inferring noalias on a null argument parameter. This
avoids a non-NFC diff in a future change.

[arsenm]

• Attributor: Don't rely on use_empty for constants #137218 👈 (View in Graphite)
• main

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[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Matt Arsenault (arsenm)

Changes

This allows inferring noalias on a null argument parameter. This
avoids a non-NFC diff in a future change.

---

Full diff: https://github.com/llvm/llvm-project/pull/137218.diff

2 Files Affected:

• (modified) llvm/lib/Transforms/IPO/AttributorAttributes.cpp (+1-1)
• (modified) llvm/test/Transforms/Attributor/issue87856.ll (+1-1)

diff --git a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
index ac56df3823e20..1032dede7cb36 100644
--- a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -5746,7 +5746,7 @@ bool AANoCapture::isImpliedByIR(Attributor &A, const IRPosition &IRP,
   assert(ImpliedAttributeKind == Attribute::Captures &&
          "Unexpected attribute kind");
   Value &V = IRP.getAssociatedValue();
-  if (!IRP.isArgumentPosition())
+  if (!isa<Constant>(V) && !IRP.isArgumentPosition())
     return V.use_empty();
 
   // You cannot "capture" null in the default address space.
diff --git a/llvm/test/Transforms/Attributor/issue87856.ll b/llvm/test/Transforms/Attributor/issue87856.ll
index 4990ef909dfaa..592ec33a31369 100644
--- a/llvm/test/Transforms/Attributor/issue87856.ll
+++ b/llvm/test/Transforms/Attributor/issue87856.ll
@@ -4,7 +4,7 @@
 define void @null_ptr_is_valid_call_with_null() #0 {
 ; CHECK-LABEL: define void @null_ptr_is_valid_call_with_null(
 ; CHECK-SAME: ) #[[ATTR0:[0-9]+]] {
-; CHECK-NEXT:    call void @store_as0(ptr nofree noundef writeonly null) #[[ATTR4:[0-9]+]]
+; CHECK-NEXT:    call void @store_as0(ptr noalias nofree noundef writeonly null) #[[ATTR4:[0-9]+]]
 ; CHECK-NEXT:    ret void
 ;
   call void @store_as0(ptr null)

[arsenm]

Merge activity

• Apr 24, 3:40 PM EDT: A user started a stack merge that includes this pull request via Graphite.
• Apr 24, 3:41 PM EDT: @arsenm merged this pull request with Graphite.