[CGP] CodeGenPrepare sinks addrspacecast

[jingyue]

Summary

Similar to bitcast, treat addrspacecast as a foldable operand.

Added a test sink-addrspacecast.ll to verify this change.

[jingyue]

ping :) it's a fairly small patch. Besides the test, I only added two lines. Thanks!

[arsenm]

LGTM

test/Transforms/CodeGenPrepare/X86/sink-addrspacecast.ll

2

Move the argument before the < %s

[jingyue]

Matt, thanks for reviewing this!

[eliben]

Committed in r209343

lib/CodeGen/CodeGenPrepare.cpp

 
 /// MightBeFoldableInst - This is a little filter, which returns true if an
 /// addressing computation involving I might be folded into a load/store
 /// accessing it.  This doesn't need to be perfect, but needs to accept at least
 /// the set of instructions that MatchOperationAddr can.
 static bool MightBeFoldableInst(Instruction *I) {
   switch (I->getOpcode()) {
   case Instruction::BitCast:
+  case Instruction::AddrSpaceCast:
     // Don't touch identity bitcasts.
     if (I->getType() == I->getOperand(0)->getType())
       return false;
     return I->getType()->isPointerTy() || I->getType()->isIntegerTy();
   case Instruction::PtrToInt:
     // PtrToInt is always a noop, as we know that the int type is pointer sized.
     return true;
   case Instruction::IntToPtr:
case Instruction::PtrToInt:
     return MatchAddr(AddrInst->getOperand(0), Depth);
   case Instruction::IntToPtr:
     // This inttoptr is a no-op if the integer type is pointer sized.
     if (TLI.getValueType(AddrInst->getOperand(0)->getType()) ==
         TLI.getPointerTy(AddrInst->getType()->getPointerAddressSpace()))
       return MatchAddr(AddrInst->getOperand(0), Depth);
     return false;
   case Instruction::BitCast:
+  case Instruction::AddrSpaceCast:
     // BitCast is always a noop, and we can handle it as long as it is
     // int->int or pointer->pointer (we don't want int<->fp or something).
     if ((AddrInst->getOperand(0)->getType()->isPointerTy() ||
          AddrInst->getOperand(0)->getType()->isIntegerTy()) &&
         // Don't touch identity bitcasts.  These were probably put here by LSR,
         // and we don't want to mess around with them.  Assume it knows what it
         // is doing.
         AddrInst->getOperand(0)->getType() != AddrInst->getType())

test/Transforms/CodeGenPrepare/X86/sink-addrspacecast.ll

+; RUN: opt -S -codegenprepare < %s | FileCheck %s
+
+target datalayout =
+"e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK-LABEL: @load_cast_gep
+; CHECK: add i64 %sunkaddr, 40
+define void @load_cast_gep(i1 %cond, i64* %base) {
+entry:
+  %addr = getelementptr inbounds i64* %base, i64 5
+  %casted = addrspacecast i64* %addr to i32 addrspace(1)*
+  br i1 %cond, label %if.then, label %fallthrough
+
+if.then:
+  %v = load i32 addrspace(1)* %casted, align 4
+  br label %fallthrough
+
+fallthrough:
+  ret void
+}
+
+; CHECK-LABEL: @store_gep_cast
+; CHECK: add i64 %sunkaddr, 20
+define void @store_gep_cast(i1 %cond, i64* %base) {
+entry:
+  %casted = addrspacecast i64* %base to i32 addrspace(1)*
+  %addr = getelementptr inbounds i32 addrspace(1)* %casted, i64 5
+  br i1 %cond, label %if.then, label %fallthrough
+
+if.then:
+  store i32 0, i32 addrspace(1)* %addr, align 4
+  br label %fallthrough
+
+fallthrough:
+  ret void
+}