[SimplifyCFG] Handle MD_noundef when hoisting common codes

[StephenFan]

Add test files.

[StephenFan]

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

1621–1622

Whether these can be replaced with combineMetadataCSE?

[StephenFan]

Fix

[nikic]

Looks like the new test fails?

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

1621–1622

Yes, let's replace this with combineMetadataForCSE

[StephenFan]

Replace with combinemetadataForCSE and make test more robust.

[nikic]

llvm/test/Transforms/SimplifyCFG/hoist-with-metadata.ll

8

Why does this no longer have range metadata? Isn't it supposed to have the merged ranges?

[StephenFan]

Add back !range metadata

[nikic]

llvm/test/Transforms/SimplifyCFG/hoist-with-metadata.ll

2

Can you please rerun it with --check-globals?

[StephenFan]

Rerun with --check-globals

[nikic]

LGTM

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

if (I1->isIdenticalToWhenDefined(I2)) {
         BIParent->splice(BI->getIterator(), BB2, I2->getIterator());
       } else {
         // For a normal instruction, we just move one to right before the
         // branch, then replace all uses of the other with the first.  Finally,
         // we remove the now redundant second instruction.
         BIParent->splice(BI->getIterator(), BB1, I1->getIterator());
         if (!I2->use_empty())
           I2->replaceAllUsesWith(I1);
         I1->andIRFlags(I2);
-        unsigned KnownIDs[] = {LLVMContext::MD_tbaa,
-                               LLVMContext::MD_range,
-                               LLVMContext::MD_fpmath,
-                               LLVMContext::MD_invariant_load,
-                               LLVMContext::MD_nonnull,
-                               LLVMContext::MD_invariant_group,
-                               LLVMContext::MD_align,
-                               LLVMContext::MD_dereferenceable,
-                               LLVMContext::MD_dereferenceable_or_null,
-                               LLVMContext::MD_mem_parallel_loop_access,
-                               LLVMContext::MD_access_group,
-                               LLVMContext::MD_preserve_access_index};
-        combineMetadata(I1, I2, KnownIDs, true);
+        combineMetadataForCSE(I1, I2, true);
 
         // I1 and I2 are being combined into a single instruction.  Its debug
         // location is the merged locations of the original instructions.
         I1->applyMergedLocation(I1->getDebugLoc(), I2->getDebugLoc());
 
         I2->eraseFromParent();
       }
       Changed = true;

llvm/test/Transforms/SimplifyCFG/hoist-with-metadata.ll

+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals
+; RUN: opt < %s -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -hoist-common-insts=true -S | FileCheck %s
+
+define void @foo(i1 %c, ptr %p) {
+; CHECK-LABEL: @foo(
+; CHECK-NEXT:  if:
+; CHECK-NEXT:    [[T:%.*]] = load i8, ptr [[P:%.*]], align 1, !range [[RNG0:![0-9]+]]
+; CHECK-NEXT:    ret void
+;
+if:
+  br i1 %c, label %then, label %else
+then:
+  %t = load i8, ptr %p, !range !0
+  br label %out
+else:
+  %e = load i8, ptr %p, !range !1
+  br label %out
+out:
+  ret void
+}
+
+define void @md_noundef_combine(i1 %c, ptr %p) {
+; CHECK-LABEL: @md_noundef_combine(
+; CHECK-NEXT:  if:
+; CHECK-NEXT:    [[T:%.*]] = load i8, ptr [[P:%.*]], align 1, !noundef !1
+; CHECK-NEXT:    ret void
+;
+if:
+  br i1 %c, label %then, label %else
+
+then:
+  %t = load i8, ptr %p, !noundef !2
+  br label %out
+
+else:
+  %e = load i8, ptr %p, !noundef !2
+  br label %out
+
+out:
+  ret void
+}
+
+define void @md_noundef_dont_combine(i1 %c, ptr %p) {
+; CHECK-LABEL: @md_noundef_dont_combine(
+; CHECK-NEXT:  if:
+; CHECK-NEXT:    [[T:%.*]] = load i8, ptr [[P:%.*]], align 1
+; CHECK-NEXT:    ret void
+;
+if:
+  br i1 %c, label %then, label %else
+
+then:
+  %t = load i8, ptr %p, !noundef !2
+  br label %out
+
+else:
+  %e = load i8, ptr %p
+  br label %out
+
+out:
+  ret void
+}
+
+!0 = !{ i8 0, i8 1 }
+!1 = !{ i8 3, i8 5 }
+!2 = !{}
+;.
+; CHECK: [[RNG0]] = !{i8 0, i8 1, i8 3, i8 5}
+; CHECK: [[META1:![0-9]+]] = !{}
+;.

llvm/test/Transforms/SimplifyCFG/hoist-with-range.ll

-; RUN: opt < %s -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -hoist-common-insts=true -S | FileCheck %s
-
-define void @foo(i1 %c, ptr %p) {
-; CHECK: if:
-; CHECK-NEXT: load i8, ptr %p, align 1, !range !0
-; CHECK: !0 = !{i8 0, i8 1, i8 3, i8 5}
-if:
-  br i1 %c, label %then, label %else
-then:
-  %t = load i8, ptr %p, !range !0
-  br label %out
-else:
-  %e = load i8, ptr %p, !range !1
-  br label %out
-out:
-  ret void
-}
-
-!0 = !{ i8 0, i8 1 }
-!1 = !{ i8 3, i8 5 }