AArch64: teach FastISel how to handle offset FrameIndices

Previously we were abandonning the attempt, leading to some combination of
extra work (when selection of a load/store fails completely) and inferior code
(when this leads to a real memcpy call instead of inlining).

rdar://problem/17187463

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210520 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Tim Northover 2014-06-10 09:52:44 +00:00
parent 292c7c6a48
commit 46b3076cd0
2 changed files with 17 additions and 6 deletions

View File

@ -463,11 +463,18 @@ bool AArch64FastISel::SimplifyAddress(Address &Addr, MVT VT,
break;
}
// FIXME: If this is a stack pointer and the offset needs to be simplified
// then put the alloca address into a register, set the base type back to
// register and continue. This should almost never happen.
//If this is a stack pointer and the offset needs to be simplified then put
// the alloca address into a register, set the base type back to register and
// continue. This should almost never happen.
if (needsLowering && Addr.getKind() == Address::FrameIndexBase) {
return false;
unsigned ResultReg = createResultReg(&AArch64::GPR64RegClass);
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(AArch64::ADDXri),
ResultReg)
.addFrameIndex(Addr.getFI())
.addImm(0)
.addImm(0);
Addr.setKind(Address::RegBase);
Addr.setReg(ResultReg);
}
// Since the offset is too large for the load/store instruction get the

View File

@ -136,9 +136,13 @@ define void @t8() {
define void @test_distant_memcpy(i8* %dst) {
; ARM64-LABEL: test_distant_memcpy:
; ARM64: bl _memcpy
; ARM64: mov [[ARRAY:x[0-9]+]], sp
; ARM64: movz [[OFFSET:x[0-9]+]], #0x1f40
; ARM64: add x[[ADDR:[0-9]+]], [[ARRAY]], [[OFFSET]]
; ARM64: ldrb [[BYTE:w[0-9]+]], [x[[ADDR]]]
; ARM64: strb [[BYTE]], [x0]
%array = alloca i8, i32 8192
%elem = getelementptr i8* %array, i32 8000
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %elem, i64 4, i32 1, i1 false)
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %elem, i64 1, i32 1, i1 false)
ret void
}