scalarizer.patch

commit a3393030cc79137c3defd1de9f31dd17bfa93d2a
Author: Nikita Popov <npopov@redhat.com>
Date:   Tue May 31 17:20:48 2022 +0200

    wip

diff --git a/llvm/lib/Transforms/Scalar/Scalarizer.cpp b/llvm/lib/Transforms/Scalar/Scalarizer.cpp
index 344f89e8ded1..4eb624e53d83 100644
--- a/llvm/lib/Transforms/Scalar/Scalarizer.cpp
+++ b/llvm/lib/Transforms/Scalar/Scalarizer.cpp
@@ -828,7 +828,10 @@ bool ScalarizerVisitor::visitExtractElementInst(ExtractElementInst &EEI) {
 
   if (auto *CI = dyn_cast<ConstantInt>(ExtIdx)) {
     Value *Res = Op0[CI->getValue().getZExtValue()];
-    gather(&EEI, {Res});
+    if (Res != &EEI) {
+      EEI.replaceAllUsesWith(Res);
+      PotentiallyDeadInstrs.emplace_back(&EEI);
+    }
     return true;
   }
 
@@ -844,7 +847,10 @@ bool ScalarizerVisitor::visitExtractElementInst(ExtractElementInst &EEI) {
     Res = Builder.CreateSelect(ShouldExtract, Elt, Res,
                                EEI.getName() + ".upto" + Twine(I));
   }
-  gather(&EEI, {Res});
+  if (Res != &EEI) {
+    EEI.replaceAllUsesWith(Res);
+    PotentiallyDeadInstrs.emplace_back(&EEI);
+  }
   return true;
 }
 
diff --git a/llvm/test/Transforms/Scalarizer/global-bug.ll b/llvm/test/Transforms/Scalarizer/global-bug.ll
index 91d1bd23af98..000ff59cb7f5 100644
--- a/llvm/test/Transforms/Scalarizer/global-bug.ll
+++ b/llvm/test/Transforms/Scalarizer/global-bug.ll
@@ -1,3 +1,4 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -passes='function(scalarizer)' -S | FileCheck %s
 
 @a = dso_local global i16 0, align 1
@@ -10,6 +11,7 @@
 define dso_local void @test1() local_unnamed_addr {
 ; CHECK-LABEL: @test1(
 ; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[EXTRACT:%.*]] = extractelement <4 x i16*> <i16* @a, i16* @a, i16* @a, i16* @a>, i32 1
 ; CHECK-NEXT:    [[T0:%.*]] = ptrtoint i16* @a to i16
 ; CHECK-NEXT:    store i16 [[T0]], i16* @b, align 1
 ; CHECK-NEXT:    ret void