From 00139e51c90d3592b2fcbae0418ea4fef736e2b3 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault@amd.com>
Date: Tue, 12 Aug 2014 19:46:13 +0000
Subject: [PATCH] Allwo bitcast + struct GEP transform to work with
 addrspacecast

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215467 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../InstCombine/InstructionCombining.cpp      | 23 ++++++++++++++++---
 test/Transforms/InstCombine/cast.ll           | 18 +++++++++++++++
 test/Transforms/InstCombine/getelementptr.ll  | 10 ++++++++
 3 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index d3648e2d050..e079eee7d2c 100644
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1667,6 +1667,18 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
   if (!DL)
     return nullptr;
 
+  // addrspacecast between types is canonicalized as a bitcast, then an
+  // addrspacecast. To take advantage of the below bitcast + struct GEP, look
+  // through the addrspacecast.
+  if (AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(PtrOp)) {
+    //   X = bitcast A addrspace(1)* to B addrspace(1)*
+    //   Y = addrspacecast A addrspace(1)* to B addrspace(2)*
+    //   Z = gep Y, <...constant indices...>
+    // Into an addrspacecasted GEP of the struct.
+    if (BitCastInst *BC = dyn_cast<BitCastInst>(ASC->getOperand(0)))
+      PtrOp = BC;
+  }
+
   /// See if we can simplify:
   ///   X = bitcast A* to B*
   ///   Y = gep X, <...constant indices...>
@@ -1675,11 +1687,10 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
   if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
     Value *Operand = BCI->getOperand(0);
     PointerType *OpType = cast<PointerType>(Operand->getType());
-    unsigned OffsetBits = DL->getPointerTypeSizeInBits(OpType);
+    unsigned OffsetBits = DL->getPointerTypeSizeInBits(GEP.getType());
     APInt Offset(OffsetBits, 0);
     if (!isa<BitCastInst>(Operand) &&
-        GEP.accumulateConstantOffset(*DL, Offset) &&
-        StrippedPtrTy->getAddressSpace() == GEP.getPointerAddressSpace()) {
+        GEP.accumulateConstantOffset(*DL, Offset)) {
 
       // If this GEP instruction doesn't move the pointer, just replace the GEP
       // with a bitcast of the real input to the dest type.
@@ -1697,6 +1708,9 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
             return &GEP;
           }
         }
+
+        if (Operand->getType()->getPointerAddressSpace() != GEP.getAddressSpace())
+          return new AddrSpaceCastInst(Operand, GEP.getType());
         return new BitCastInst(Operand, GEP.getType());
       }
 
@@ -1712,6 +1726,9 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
         if (NGEP->getType() == GEP.getType())
           return ReplaceInstUsesWith(GEP, NGEP);
         NGEP->takeName(&GEP);
+
+        if (NGEP->getType()->getPointerAddressSpace() != GEP.getAddressSpace())
+          return new AddrSpaceCastInst(NGEP, GEP.getType());
         return new BitCastInst(NGEP, GEP.getType());
       }
     }
diff --git a/test/Transforms/InstCombine/cast.ll b/test/Transforms/InstCombine/cast.ll
index 0cbfbb071bb..86e9f3f5335 100644
--- a/test/Transforms/InstCombine/cast.ll
+++ b/test/Transforms/InstCombine/cast.ll
@@ -354,6 +354,24 @@ define i32* @test41(i32* %tmp1) {
 ; CHECK: ret i32* %tmp1
 }
 
+define i32 addrspace(1)* @test41_addrspacecast_smaller(i32* %tmp1) {
+  %tmp64 = addrspacecast i32* %tmp1 to { i32 } addrspace(1)*
+  %tmp65 = getelementptr { i32 } addrspace(1)* %tmp64, i32 0, i32 0
+  ret i32 addrspace(1)* %tmp65
+; CHECK-LABEL: @test41_addrspacecast_smaller(
+; CHECK: addrspacecast i32* %tmp1 to i32 addrspace(1)*
+; CHECK-NEXT: ret i32 addrspace(1)*
+}
+
+define i32* @test41_addrspacecast_larger(i32 addrspace(1)* %tmp1) {
+  %tmp64 = addrspacecast i32 addrspace(1)* %tmp1 to { i32 }*
+  %tmp65 = getelementptr { i32 }* %tmp64, i32 0, i32 0
+  ret i32* %tmp65
+; CHECK-LABEL: @test41_addrspacecast_larger(
+; CHECK: addrspacecast i32 addrspace(1)* %tmp1 to i32*
+; CHECK-NEXT: ret i32*
+}
+
 define i32 @test42(i32 %X) {
         %Y = trunc i32 %X to i8         ; <i8> [#uses=1]
         %Z = zext i8 %Y to i32          ; <i32> [#uses=1]
diff --git a/test/Transforms/InstCombine/getelementptr.ll b/test/Transforms/InstCombine/getelementptr.ll
index 3240c6d2a4d..da91ada0805 100644
--- a/test/Transforms/InstCombine/getelementptr.ll
+++ b/test/Transforms/InstCombine/getelementptr.ll
@@ -580,6 +580,16 @@ define i32 addrspace(1)* @test33_array_struct_as1([10 x %struct.Key] addrspace(1
   ret i32 addrspace(1)* %C
 }
 
+define i32 addrspace(1)* @test33_addrspacecast(%struct.Key* %A) {
+; CHECK-LABEL: @test33_addrspacecast(
+; CHECK: %C = getelementptr %struct.Key* %A, i64 0, i32 0, i32 1
+; CHECK-NEXT: addrspacecast i32* %C to i32 addrspace(1)*
+; CHECK-NEXT: ret
+  %B = addrspacecast %struct.Key* %A to %struct.anon addrspace(1)*
+  %C = getelementptr %struct.anon addrspace(1)* %B, i32 0, i32 2
+  ret i32 addrspace(1)* %C
+}
+
 	%T2 = type { i8*, i8 }
 define i8* @test34(i8* %Val, i64 %V) nounwind {
 entry:
-- 
2.34.1