[Local] Preserve !nonnull only when K dominate J and K has a !noundef

[StephenFan]

Summary

Similar to D142687

[nikic]

LGTM

llvm/lib/Transforms/Utils/Local.cpp

switch (Kind) {
       case LLVMContext::MD_fpmath:
         K->setMetadata(Kind, MDNode::getMostGenericFPMath(JMD, KMD));
         break;
       case LLVMContext::MD_invariant_load:
         // Only set the !invariant.load if it is present in both instructions.
         K->setMetadata(Kind, JMD);
         break;
       case LLVMContext::MD_nonnull:
-        // If K does move, keep nonull if it is present in both instructions.
-        if (DoesKMove)
+        if (DoesKMove || !K->hasMetadata(LLVMContext::MD_noundef))
           K->setMetadata(Kind, JMD);
         break;
       case LLVMContext::MD_invariant_group:
         // Preserve !invariant.group in K.
         break;
       case LLVMContext::MD_align:
         K->setMetadata(Kind,
           MDNode::getMostGenericAlignmentOrDereferenceable(JMD, KMD));

llvm/test/Transforms/InstCombine/load-combine-metadata-dominance.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
 ; RUN: opt -passes=instcombine -S < %s | FileCheck %s
 
 target datalayout = "e-m:e-p:64:64:64-i64:64-f80:128-n8:16:32:64-S128"
 
-; Check that nonnull metadata is propagated from dominating load.
+; Check that nonnull metadata is not propagated from dominating load.
 define void @combine_metadata_dominance1(ptr %p) {
 ; CHECK-LABEL: define void @combine_metadata_dominance1
 ; CHECK-SAME: (ptr [[P:%.*]]) {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[BB1:%.*]]
 ; CHECK:       bb1:
-; CHECK-NEXT:    [[A:%.*]] = load ptr, ptr [[P]], align 8, !nonnull !0
+; CHECK-NEXT:    [[A:%.*]] = load ptr, ptr [[P]], align 8
 ; CHECK-NEXT:    store i32 0, ptr [[A]], align 4
 ; CHECK-NEXT:    ret void
 ;
 entry:
   %a = load ptr, ptr %p, !nonnull !0
   br label %bb1
 
 bb1:
bb1:
   store i32 0, ptr %a
   store i32 0, ptr %b
   ret void
 
 bb2:
   ret void
 }
 
+define void @combine_metadata_dominance3(ptr %p) {
+; CHECK-LABEL: define void @combine_metadata_dominance3
+; CHECK-SAME: (ptr [[P:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[BB1:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[A:%.*]] = load ptr, ptr [[P]], align 8, !nonnull !0, !noundef !0
+; CHECK-NEXT:    store i32 0, ptr [[A]], align 4
+; CHECK-NEXT:    ret void
+;
+entry:
+  %a = load ptr, ptr %p, !nonnull !0, !noundef !1
+  br label %bb1
+
+bb1:
+  %b = load ptr, ptr %p
+  store i32 0, ptr %a
+  store i32 0, ptr %b
+  ret void
+}
+
+define void @combine_metadata_dominance4(ptr %p) {
+; CHECK-LABEL: define void @combine_metadata_dominance4
+; CHECK-SAME: (ptr [[P:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[BB1:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[A:%.*]] = load ptr, ptr [[P]], align 8
+; CHECK-NEXT:    store i32 0, ptr [[A]], align 4
+; CHECK-NEXT:    ret void
+;
+entry:
+  %a = load ptr, ptr %p, !nonnull !0
+  br label %bb1
 
+bb1:
+  %b = load ptr, ptr %p, !noundef !1
+  store i32 0, ptr %a
+  store i32 0, ptr %b
+  ret void
+}
 !0 = !{}
+!1 = !{}

llvm/test/Transforms/NewGVN/metadata-nonnull.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
 ; RUN: opt %s -passes=newgvn -S | FileCheck %s
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 define ptr @test1(ptr %v0, ptr %v1) {
 ; CHECK-LABEL: define ptr @test1
 ; CHECK-SAME: (ptr [[V0:%.*]], ptr [[V1:%.*]]) {
 ; CHECK-NEXT:  top:
-; CHECK-NEXT:    [[V2:%.*]] = load ptr, ptr [[V0]], align 8, !nonnull !0
+; CHECK-NEXT:    [[V2:%.*]] = load ptr, ptr [[V0]], align 8
 ; CHECK-NEXT:    store ptr [[V2]], ptr [[V1]], align 8
 ; CHECK-NEXT:    ret ptr [[V2]]
 ;
 top:
   %v2 = load ptr, ptr %v0, !nonnull !0
   store ptr %v2, ptr %v1
   %v3 = load ptr, ptr %v1
   ret ptr %v3
bb2:
   %v3 = load ptr, ptr %v0, !nonnull !0
   ret ptr %v3
 }
 
 define ptr @test5(ptr %v0) {
 ; CHECK-LABEL: define ptr @test5
 ; CHECK-SAME: (ptr [[V0:%.*]]) {
 ; CHECK-NEXT:  top:
-; CHECK-NEXT:    [[V1:%.*]] = load ptr, ptr [[V0]], align 8, !nonnull !0
+; CHECK-NEXT:    [[V1:%.*]] = load ptr, ptr [[V0]], align 8
 ; CHECK-NEXT:    call void @use1(ptr [[V1]])
 ; CHECK-NEXT:    br i1 undef, label [[BB1:%.*]], label [[BB2:%.*]]
 ; CHECK:       bb1:
 ; CHECK-NEXT:    ret ptr [[V1]]
 ; CHECK:       bb2:
 ; CHECK-NEXT:    ret ptr [[V1]]
 ;
 top:

 }
 
 define ptr @test6(ptr %v0, ptr %v1) {
 ; CHECK-LABEL: define ptr @test6
 ; CHECK-SAME: (ptr [[V0:%.*]], ptr [[V1:%.*]]) {
 ; CHECK-NEXT:  top:
 ; CHECK-NEXT:    br i1 undef, label [[BB1:%.*]], label [[BB2:%.*]]
 ; CHECK:       bb1:
-; CHECK-NEXT:    [[V2:%.*]] = load ptr, ptr [[V0]], align 8, !nonnull !0
+; CHECK-NEXT:    [[V2:%.*]] = load ptr, ptr [[V0]], align 8
 ; CHECK-NEXT:    store ptr [[V2]], ptr [[V1]], align 8
 ; CHECK-NEXT:    ret ptr [[V2]]
 ; CHECK:       bb2:
 ; CHECK-NEXT:    [[V4:%.*]] = load ptr, ptr [[V0]], align 8
 ; CHECK-NEXT:    store ptr [[V4]], ptr [[V1]], align 8
 ; CHECK-NEXT:    ret ptr [[V4]]
 ;
 top: