[PATCH] D148129: [GVN] Adjust metadata for coerced load CSE

[Nikita Popov via Phabricator via llvm-commits]

nikic updated this revision to Diff 513510.
nikic added a comment.

Preserve dereferenceable and dereferenceable_or_null.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D148129/new/

https://reviews.llvm.org/D148129

Files:
  llvm/lib/Transforms/Scalar/GVN.cpp
  llvm/test/Transforms/GVN/metadata.ll


Index: llvm/test/Transforms/GVN/metadata.ll
===================================================================
--- llvm/test/Transforms/GVN/metadata.ll
+++ llvm/test/Transforms/GVN/metadata.ll
@@ -168,7 +168,7 @@
 define void @load_ptr_nonnull_to_i64(ptr %p) {
 ; CHECK-LABEL: define void @load_ptr_nonnull_to_i64
 ; CHECK-SAME: (ptr [[P:%.*]]) {
-; CHECK-NEXT:    [[VAL:%.*]] = load ptr, ptr [[P]], align 8, !nonnull !6
+; CHECK-NEXT:    [[VAL:%.*]] = load ptr, ptr [[P]], align 8
 ; CHECK-NEXT:    [[VAL_INT:%.*]] = ptrtoint ptr [[VAL]] to i64
 ; CHECK-NEXT:    call void @use.i64(i64 [[VAL_INT]])
 ; CHECK-NEXT:    call void @use.i64(i64 [[VAL_INT]])
@@ -253,7 +253,7 @@
 define void @load_ptr_nonnull_to_i32(ptr %p) {
 ; CHECK-LABEL: define void @load_ptr_nonnull_to_i32
 ; CHECK-SAME: (ptr [[P:%.*]]) {
-; CHECK-NEXT:    [[VAL:%.*]] = load ptr, ptr [[P]], align 8, !nonnull !6
+; CHECK-NEXT:    [[VAL:%.*]] = load ptr, ptr [[P]], align 8
 ; CHECK-NEXT:    [[VAL_INT:%.*]] = ptrtoint ptr [[VAL]] to i64
 ; CHECK-NEXT:    [[TMP1:%.*]] = trunc i64 [[VAL_INT]] to i32
 ; CHECK-NEXT:    call void @use.i64(i64 [[VAL_INT]])
@@ -271,7 +271,7 @@
 define void @load_i64_range_to_i32_range(ptr %p) {
 ; CHECK-LABEL: define void @load_i64_range_to_i32_range
 ; CHECK-SAME: (ptr [[P:%.*]]) {
-; CHECK-NEXT:    [[VAL:%.*]] = load i64, ptr [[P]], align 8, !range [[RNG8:![0-9]+]]
+; CHECK-NEXT:    [[VAL:%.*]] = load i64, ptr [[P]], align 8
 ; CHECK-NEXT:    [[TMP1:%.*]] = trunc i64 [[VAL]] to i32
 ; CHECK-NEXT:    call void @use.i64(i64 [[VAL]])
 ; CHECK-NEXT:    call void @use.i32(i32 [[TMP1]])
@@ -305,5 +305,4 @@
 ; CHECK: [[RNG5]] = !{i32 3, i32 4, i32 5, i32 2}
 ; CHECK: [[META6:![0-9]+]] = !{}
 ; CHECK: [[META7:![0-9]+]] = !{i64 10}
-; CHECK: [[RNG8]] = !{i64 0, i64 10}
 ;.
Index: llvm/lib/Transforms/Scalar/GVN.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/GVN.cpp
+++ llvm/lib/Transforms/Scalar/GVN.cpp
@@ -999,6 +999,18 @@
       Res = CoercedLoad;
     } else {
       Res = getValueForLoad(CoercedLoad, Offset, LoadTy, InsertPt, DL);
+      // We are adding a new user for this load, for which the original
+      // metadata may not hold. Additionally, the new load may have a different
+      // size and type, so their metadata cannot be combined in any
+      // straightforward way.
+      // Drop all metadata that is not known to cause immediate UB on violation,
+      // unless the load has !noundef, in which case all metadata violations
+      // will be promoted to UB.
+      if (!CoercedLoad->hasMetadata(LLVMContext::MD_noundef))
+        CoercedLoad->dropUnknownNonDebugMetadata(
+            {LLVMContext::MD_dereferenceable,
+             LLVMContext::MD_dereferenceable_or_null,
+             LLVMContext::MD_invariant_load, LLVMContext::MD_invariant_group});
       LLVM_DEBUG(dbgs() << "GVN COERCED NONLOCAL LOAD:\nOffset: " << Offset
                         << "  " << *getCoercedLoadValue() << '\n'
                         << *Res << '\n'


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