[PATCH] D105733: [OpaquePtr] Require matching signature in getCalledFunction()

[Nikita Popov via Phabricator via llvm-commits]

nikic created this revision.
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With opaque pointers, it's possible to directly call a function with a different signature, without an intermediate bitcast. However, lot's of code using getCalledFunction() reasonably assumes that the signatures match (which is always true without opaque pointers). Add an explicit check to that effect.

The test case is from D105313 <https://reviews.llvm.org/D105313>, where I ran into the problem, but on further investigation this also affects lots of other code, we just have little coverage with mismatching signatures. The change from D105313 <https://reviews.llvm.org/D105313> is still desirable for other reasons, but this patch addresses (I believe) the root problem when it comes to opaque pointers.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D105733

Files:
  llvm/include/llvm/IR/InstrTypes.h
  llvm/test/Transforms/InstSimplify/known-non-zero-opaque-ptrs.ll


Index: llvm/test/Transforms/InstSimplify/known-non-zero-opaque-ptrs.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/InstSimplify/known-non-zero-opaque-ptrs.ll
@@ -0,0 +1,51 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -instsimplify -force-opaque-pointers < %s | FileCheck %s
+
+declare void @zero_args()
+declare void @two_args(ptr, ptr)
+
+; TODO: Could be non-null based on call-site attributes.
+define i1 @test_zero_args_nonnull(ptr %p) {
+; CHECK-LABEL: @test_zero_args_nonnull(
+; CHECK-NEXT:    call void @zero_args(ptr noundef nonnull [[P:%.*]])
+; CHECK-NEXT:    [[C:%.*]] = icmp ne ptr [[P]], null
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  call void @zero_args(ptr nonnull noundef %p)
+  %c = icmp ne ptr %p, null
+  ret i1 %c
+}
+
+define i1 @test_zero_args_maybe_null(ptr %p) {
+; CHECK-LABEL: @test_zero_args_maybe_null(
+; CHECK-NEXT:    call void @zero_args(ptr [[P:%.*]])
+; CHECK-NEXT:    [[C:%.*]] = icmp ne ptr [[P]], null
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  call void @zero_args(ptr %p)
+  %c = icmp ne ptr %p, null
+  ret i1 %c
+}
+
+; TODO: Could be non-null based on call-site attributes.
+define i1 @test_two_args_nonnull(ptr %p) {
+; CHECK-LABEL: @test_two_args_nonnull(
+; CHECK-NEXT:    call void @two_args(ptr noundef nonnull [[P:%.*]])
+; CHECK-NEXT:    [[C:%.*]] = icmp ne ptr [[P]], null
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  call void @two_args(ptr nonnull noundef %p)
+  %c = icmp ne ptr %p, null
+  ret i1 %c
+}
+
+define i1 @test_two_args_maybe_null(ptr %p) {
+; CHECK-LABEL: @test_two_args_maybe_null(
+; CHECK-NEXT:    call void @two_args(ptr [[P:%.*]])
+; CHECK-NEXT:    [[C:%.*]] = icmp ne ptr [[P]], null
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  call void @two_args(ptr %p)
+  %c = icmp ne ptr %p, null
+  ret i1 %c
+}
Index: llvm/include/llvm/IR/InstrTypes.h
===================================================================
--- llvm/include/llvm/IR/InstrTypes.h
+++ llvm/include/llvm/IR/InstrTypes.h
@@ -1391,7 +1391,12 @@
   /// Returns the function called, or null if this is an
   /// indirect function invocation.
   Function *getCalledFunction() const {
-    return dyn_cast_or_null<Function>(getCalledOperand());
+    // With opaque pointers, only consider it a direct call if the declaration
+    // signature matches the call signature.
+    if (auto *F = dyn_cast<Function>(getCalledOperand()))
+      if (F->getValueType() == getFunctionType())
+        return F;
+    return nullptr;
   }
 
   /// Return true if the callsite is an indirect call.


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