From 315eafc33980be8a90b16e48bdf551f517b55c48 Mon Sep 17 00:00:00 2001
From: Artur Pilipenko <apilipenko@azulsystems.com>
Date: Thu, 25 May 2017 15:14:48 +0000
Subject: [PATCH] [InstCombine] Teach isAllocSiteRemovable to look through
 addrspacecasts

Reviewed By: reames

Differential Revision: https://reviews.llvm.org/D28565

llvm-svn: 303870
---
 llvm/lib/Transforms/InstCombine/InstructionCombining.cpp | 4 +++-
 llvm/test/Transforms/InstCombine/alloca.ll               | 7 +++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 90b024b..2730afc 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1963,6 +1963,7 @@ static bool isAllocSiteRemovable(Instruction *AI,
         // Give up the moment we see something we can't handle.
         return false;
 
+      case Instruction::AddrSpaceCast:
       case Instruction::BitCast:
       case Instruction::GetElementPtr:
         Users.emplace_back(I);
@@ -2064,7 +2065,8 @@ Instruction *InstCombiner::visitAllocSite(Instruction &MI) {
         replaceInstUsesWith(*C,
                             ConstantInt::get(Type::getInt1Ty(C->getContext()),
                                              C->isFalseWhenEqual()));
-      } else if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I)) {
+      } else if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I) ||
+                 isa<AddrSpaceCastInst>(I)) {
         replaceInstUsesWith(*I, UndefValue::get(I->getType()));
       }
       eraseInstFromFunction(*I);
diff --git a/llvm/test/Transforms/InstCombine/alloca.ll b/llvm/test/Transforms/InstCombine/alloca.ll
index f81f700..490830a 100644
--- a/llvm/test/Transforms/InstCombine/alloca.ll
+++ b/llvm/test/Transforms/InstCombine/alloca.ll
@@ -51,8 +51,8 @@ define i32* @test4(i32 %n) {
   ret i32* %A
 }
 
-; Allocas which are only used by GEPs, bitcasts, and stores (transitively)
-; should be deleted.
+; Allocas which are only used by GEPs, bitcasts, addrspacecasts, and stores
+; (transitively) should be deleted.
 define void @test5() {
 ; CHECK-LABEL: @test5(
 ; CHECK-NOT: alloca
@@ -62,6 +62,7 @@ define void @test5() {
 entry:
   %a = alloca { i32 }
   %b = alloca i32*
+  %c = alloca i32
   %a.1 = getelementptr { i32 }, { i32 }* %a, i32 0, i32 0
   store i32 123, i32* %a.1
   store i32* %a.1, i32** %b
@@ -73,6 +74,8 @@ entry:
   store atomic i32 3, i32* %a.3 release, align 4
   %a.4 = getelementptr { i32 }, { i32 }* %a, i32 0, i32 0
   store atomic i32 4, i32* %a.4 seq_cst, align 4
+  %c.1 = addrspacecast i32* %c to i32 addrspace(1)*
+  store i32 123, i32 addrspace(1)* %c.1
   ret void
 }
 
-- 
2.7.4