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Lower TAGPstack with negative offset to SUBG. 

Summary:
This never really occurs in the current codegen, so only a MIR test is
possible.

Reviewers: ostannard, pcc

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D72123
This commit is contained in:
Evgenii Stepanov 2019-12-09 16:52:31 -08:00
parent df3f4e0d77
commit 40a80a0a19
3 changed files with 49 additions and 3 deletions
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6
llvm/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
View File

@ -696,10 +696,12 @@ bool AArch64ExpandPseudo::expandMI(MachineBasicBlock &MBB,
return true;
}
case AArch64::TAGPstack: {
BuildMI(MBB, MBBI, MI.getDebugLoc(), TII->get(AArch64::ADDG))
int64_t Offset = MI.getOperand(2).getImm();
BuildMI(MBB, MBBI, MI.getDebugLoc(),
TII->get(Offset >= 0 ? AArch64::ADDG : AArch64::SUBG))
.add(MI.getOperand(0))
.add(MI.getOperand(1))
.add(MI.getOperand(2))
.addImm(std::abs(Offset))
.add(MI.getOperand(4));
MI.eraseFromParent();
return true;

9
llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
View File

@ -2188,12 +2188,19 @@ bool AArch64InstrInfo::getMemOpInfo(unsigned Opcode, unsigned &Scale,
MaxOffset = 4095;
break;
case AArch64::ADDG:
case AArch64::TAGPstack:
Scale = 16;
Width = 0;
MinOffset = 0;
MaxOffset = 63;
break;
case AArch64::TAGPstack:
Scale = 16;
Width = 0;
// TAGP with a negative offset turns into SUBP, which has a maximum offset
// of 63 (not 64!).
MinOffset = -63;
MaxOffset = 63;
break;
case AArch64::LDG:
case AArch64::STGOffset:
case AArch64::STZGOffset:

37
llvm/test/CodeGen/AArch64/addg_subg.mir Normal file
View File

@ -0,0 +1,37 @@
# RUN: llc -mtriple=aarch64 -run-pass=prologepilog,aarch64-expand-pseudo %s -o - | FileCheck %s
# CHECK: renamable $x8 = IRG $sp, $xzr
# CHECK: renamable $x0 = ADDG $x8, 0, 0
# CHECK: renamable $x0 = ADDG $x8, 5, 0
# CHECK: renamable $x0 = ADDG $x8, 63, 0
# CHECK: $[[R:x[0-9]+]] = ADDXri $x8, 16, 0
# CHECK: renamable $x0 = ADDG killed $[[R]], 63, 0
# CHECK: renamable $x0 = SUBG $x8, 5, 0
# CHECK: renamable $x0 = SUBG $x8, 63, 0
# CHECK: $[[R:x[0-9]+]] = SUBXri $x8, 16, 0
# CHECK: renamable $x0 = SUBG killed $[[R]], 63, 0
---
name: subg
stack:
- { id: 0, type: default, offset: 0, size: 16, alignment: 16,
stack-id: default, callee-saved-register: '', callee-saved-restored: true,
local-offset: -16, debug-info-variable: '', debug-info-expression: '',
debug-info-location: '' }
body: |
bb.0.entry:
renamable $x8 = IRGstack $sp, $xzr
renamable $x0 = TAGPstack %stack.0, 0, killed renamable $x8, 0
renamable $x0 = TAGPstack %stack.0, 5, killed renamable $x8, 0
renamable $x0 = TAGPstack %stack.0, 63, killed renamable $x8, 0
renamable $x0 = TAGPstack %stack.0, 64, killed renamable $x8, 0
renamable $x0 = TAGPstack %stack.0, -5, killed renamable $x8, 0
renamable $x0 = TAGPstack %stack.0, -63, killed renamable $x8, 0
renamable $x0 = TAGPstack %stack.0, -64, killed renamable $x8, 0
RET_ReallyLR
...