[llvm] ef48436 - [AttributeFuncs] Consider `noundef` in `typeIncompatible`

[Johannes Doerfert via llvm-commits]

Author: Johannes Doerfert
Date: 2020-10-05T23:23:06-05:00
New Revision: ef48436e62732e61cea5dde9b35b63b3ce8126f7

URL: https://github.com/llvm/llvm-project/commit/ef48436e62732e61cea5dde9b35b63b3ce8126f7
DIFF: https://github.com/llvm/llvm-project/commit/ef48436e62732e61cea5dde9b35b63b3ce8126f7.diff

LOG: [AttributeFuncs] Consider `noundef` in `typeIncompatible`

Drop `noundef` for return values that are replaced by void and make it
illegal to put `noundef` on a void value.

Reviewed By: fhahn

Differential Revision: https://reviews.llvm.org/D87306

Added: 
    llvm/test/Verifier/noundef.ll

Modified: 
    llvm/lib/IR/Attributes.cpp
    llvm/test/Transforms/DeadArgElim/returned.ll
    llvm/test/Verifier/align.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
index ecb0bd693edd..b21d45274842 100644
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -1859,6 +1859,10 @@ AttrBuilder AttributeFuncs::typeIncompatible(Type *Ty) {
         .addByValAttr(Ty)
         .addByRefAttr(Ty);
 
+  // Some attributes can apply to all "values" but there are no `void` values.
+  if (Ty->isVoidTy())
+    Incompatible.addAttribute(Attribute::NoUndef);
+
   return Incompatible;
 }
 

diff  --git a/llvm/test/Transforms/DeadArgElim/returned.ll b/llvm/test/Transforms/DeadArgElim/returned.ll
index 0b00a116624b..e96faea6e9f6 100644
--- a/llvm/test/Transforms/DeadArgElim/returned.ll
+++ b/llvm/test/Transforms/DeadArgElim/returned.ll
@@ -45,7 +45,7 @@ define internal %Ty* @test5(%Ty* %this) {
 
 ; Drop all these attributes
 ; CHECK-LABEL: define internal void @test6
-define internal align 8 dereferenceable_or_null(2) noalias i8* @test6() {
+define internal align 8 dereferenceable_or_null(2) noundef noalias i8* @test6() {
   ret i8* null
 }
 

diff  --git a/llvm/test/Verifier/align.ll b/llvm/test/Verifier/align.ll
index 762249aa6b11..38ce3772e765 100644
--- a/llvm/test/Verifier/align.ll
+++ b/llvm/test/Verifier/align.ll
@@ -6,7 +6,7 @@ define void @align_non_pointer1(i32 align 4 %a) {
   ret void
 }
 
-; CHECK: Wrong types for attribute: inalloca nest noalias nocapture nonnull readnone readonly signext zeroext byref(void) byval(void) preallocated(void) sret(void) align 1 dereferenceable(1) dereferenceable_or_null(1)
+; CHECK: Wrong types for attribute: inalloca nest noalias nocapture noundef nonnull readnone readonly signext zeroext byref(void) byval(void) preallocated(void) sret(void) align 1 dereferenceable(1) dereferenceable_or_null(1)
 ; CHECK-NEXT: @align_non_pointer2
 define align 4 void @align_non_pointer2(i32 %a) {
   ret void

diff  --git a/llvm/test/Verifier/noundef.ll b/llvm/test/Verifier/noundef.ll
new file mode 100644
index 000000000000..7b199cd6d2de
--- /dev/null
+++ b/llvm/test/Verifier/noundef.ll
@@ -0,0 +1,7 @@
+; RUN: not llvm-as < %s -o /dev/null 2>&1 | FileCheck %s
+
+; CHECK: Wrong types for attribute: inalloca nest noalias nocapture noundef nonnull readnone readonly signext zeroext byref(void) byval(void) preallocated(void) sret(void) align 1 dereferenceable(1) dereferenceable_or_null(1)
+; CHECK-NEXT: @noundef_void
+define noundef void @noundef_void() {
+  ret void
+}