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[FastISel][AArch64] Fold 'AND' instruction during the address computation.

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The 'AND' instruction could be used to mask out the lower 32 bits of a register.
If this is done inside an address computation we might be able to fold the
instruction into the memory instruction itself.

and  x1, x1, #0xffffffff   ---> ldrb x0, [x0, w1, uxtw]
ldrb x0, [x0, x1]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218030 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Juergen Ributzka 2014-09-18 05:40:41 +00:00
parent 49ab1a424d
commit ffbd4879eb
2 changed files with 99 additions and 2 deletions
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54
lib/Target/AArch64/AArch64FastISel.cpp
View File

@ -596,6 +596,29 @@ bool AArch64FastISel::computeAddress(const Value *Obj, Address &Addr, Type *Ty)
if (SE->getOperand(0)->getType()->isIntegerTy(32))
Addr.setExtendType(AArch64_AM::SXTW);
if (const auto *AI = dyn_cast<BinaryOperator>(U))
if (AI->getOpcode() == Instruction::And) {
const Value *LHS = AI->getOperand(0);
const Value *RHS = AI->getOperand(1);
if (const auto *C = dyn_cast<ConstantInt>(LHS))
if (C->getValue() == 0xffffffff)
std::swap(LHS, RHS);
if (const auto *C = cast<ConstantInt>(RHS))
if (C->getValue() == 0xffffffff) {
Addr.setExtendType(AArch64_AM::UXTW);
unsigned Reg = getRegForValue(LHS);
if (!Reg)
return false;
bool RegIsKill = hasTrivialKill(LHS);
Reg = fastEmitInst_extractsubreg(MVT::i32, Reg, RegIsKill,
AArch64::sub_32);
Addr.setOffsetReg(Reg);
return true;
}
}
unsigned Reg = getRegForValue(U->getOperand(0));
if (!Reg)
return false;
@ -660,6 +683,37 @@ bool AArch64FastISel::computeAddress(const Value *Obj, Address &Addr, Type *Ty)
Addr.setOffsetReg(Reg);
return true;
}
case Instruction::And: {
if (Addr.getOffsetReg())
break;
if (DL.getTypeSizeInBits(Ty) != 8)
break;
const Value *LHS = U->getOperand(0);
const Value *RHS = U->getOperand(1);
if (const auto *C = dyn_cast<ConstantInt>(LHS))
if (C->getValue() == 0xffffffff)
std::swap(LHS, RHS);
if (const auto *C = cast<ConstantInt>(RHS))
if (C->getValue() == 0xffffffff) {
Addr.setShift(0);
Addr.setExtendType(AArch64_AM::LSL);
Addr.setExtendType(AArch64_AM::UXTW);
unsigned Reg = getRegForValue(LHS);
if (!Reg)
return false;
bool RegIsKill = hasTrivialKill(LHS);
Reg = fastEmitInst_extractsubreg(MVT::i32, Reg, RegIsKill,
AArch64::sub_32);
Addr.setOffsetReg(Reg);
return true;
}
break;
}
} // end switch
if (Addr.getReg()) {

45
test/CodeGen/AArch64/fast-isel-addressing-modes.ll
View File

@ -1,5 +1,5 @@
; RUN: llc -mtriple=aarch64-apple-darwin -verify-machineinstrs < %s | FileCheck %s --check-prefix=CHECK --check-prefix=SDAG
; RUN: llc -mtriple=aarch64-apple-darwin -O0 -fast-isel-abort -verify-machineinstrs < %s | FileCheck %s --check-prefix=CHECK --check-prefix=FAST
; RUN: llc -mtriple=aarch64-apple-darwin -fast-isel -fast-isel-abort -verify-machineinstrs < %s | FileCheck %s --check-prefix=CHECK --check-prefix=FAST
; Load / Store Base Register only
define zeroext i1 @load_breg_i1(i1* %a) {
@ -425,6 +425,49 @@ define i32 @load_breg_mul_offreg_1(i64 %a, i64 %b) {
ret i32 %4
}
define zeroext i8 @load_breg_and_offreg_1(i64 %a, i64 %b) {
; CHECK-LABEL: load_breg_and_offreg_1
; CHECK: ldrb {{w[0-9]+}}, [x1, w0, uxtw]
%1 = and i64 %a, 4294967295
%2 = add i64 %1, %b
%3 = inttoptr i64 %2 to i8*
%4 = load i8* %3
ret i8 %4
}
define zeroext i16 @load_breg_and_offreg_2(i64 %a, i64 %b) {
; CHECK-LABEL: load_breg_and_offreg_2
; CHECK: ldrh {{w[0-9]+}}, [x1, w0, uxtw #1]
%1 = and i64 %a, 4294967295
%2 = shl i64 %1, 1
%3 = add i64 %2, %b
%4 = inttoptr i64 %3 to i16*
%5 = load i16* %4
ret i16 %5
}
define i32 @load_breg_and_offreg_3(i64 %a, i64 %b) {
; CHECK-LABEL: load_breg_and_offreg_3
; CHECK: ldr {{w[0-9]+}}, [x1, w0, uxtw #2]
%1 = and i64 %a, 4294967295
%2 = shl i64 %1, 2
%3 = add i64 %2, %b
%4 = inttoptr i64 %3 to i32*
%5 = load i32* %4
ret i32 %5
}
define i64 @load_breg_and_offreg_4(i64 %a, i64 %b) {
; CHECK-LABEL: load_breg_and_offreg_4
; CHECK: ldr {{x[0-9]+}}, [x1, w0, uxtw #3]
%1 = and i64 %a, 4294967295
%2 = shl i64 %1, 3
%3 = add i64 %2, %b
%4 = inttoptr i64 %3 to i64*
%5 = load i64* %4
ret i64 %5
}
; Load Base Register + Scaled Register Offset + Sign/Zero extension
define i32 @load_breg_zext_shift_offreg_1(i32 %a, i64 %b) {
; CHECK-LABEL: load_breg_zext_shift_offreg_1