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[PowerPC] Add option to control PCRel GOT indirect linker optimization 

Add a hidden option to the compiler to control a the PC Relative GOT indirect
linker optimization.

If this option is set to false the compiler will no loger produce the
relocations required by the linker to perform the optimization.

Reviewed By: nemanjai, NeHuang, #powerpc

Differential Revision: https://reviews.llvm.org/D85377
This commit is contained in:
Stefan Pintilie 2020-08-10 08:47:09 -05:00
parent 4f9f4b21e0
commit 81883ca074
2 changed files with 47 additions and 0 deletions
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8
llvm/lib/Target/PowerPC/PPCPreEmitPeephole.cpp
View File

@ -38,6 +38,10 @@ STATISTIC(NumberOfSelfCopies,
STATISTIC(NumFrameOffFoldInPreEmit,
"Number of folding frame offset by using r+r in pre-emit peephole");
static cl::opt<bool>
EnablePCRelLinkerOpt("ppc-pcrel-linker-opt", cl::Hidden, cl::init(true),
cl::desc("enable PC Relative linker optimization"));
static cl::opt<bool>
RunPreEmitPeephole("ppc-late-peephole", cl::Hidden, cl::init(true),
cl::desc("Run pre-emit peephole optimizations."));
@ -234,6 +238,10 @@ static bool hasPCRelativeForm(MachineInstr &Use) {
bool addLinkerOpt(MachineBasicBlock &MBB, const TargetRegisterInfo *TRI) {
MachineFunction *MF = MBB.getParent();
// If the linker opt is disabled then just return.
if (!EnablePCRelLinkerOpt)
return false;
// Add this linker opt only if we are using PC Relative memops.
if (!MF->getSubtarget<PPCSubtarget>().isUsingPCRelativeCalls())
return false;

39
llvm/test/CodeGen/PowerPC/pcrel-linkeropt-option.ll Normal file
View File

@ -0,0 +1,39 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -verify-machineinstrs -mtriple=powerpc64le-unknown-linux-gnu \
; RUN: -mcpu=pwr10 -ppc-asm-full-reg-names -ppc-vsr-nums-as-vr \
; RUN: < %s | FileCheck %s --check-prefix=DEFAULT
; RUN: llc -verify-machineinstrs -mtriple=powerpc64le-unknown-linux-gnu \
; RUN: -mcpu=pwr10 -ppc-asm-full-reg-names -ppc-vsr-nums-as-vr \
; RUN: -ppc-pcrel-linker-opt=true < %s | FileCheck %s --check-prefix=ON
; RUN: llc -verify-machineinstrs -mtriple=powerpc64le-unknown-linux-gnu \
; RUN: -mcpu=pwr10 -ppc-asm-full-reg-names -ppc-vsr-nums-as-vr \
; RUN: -ppc-pcrel-linker-opt=false < %s | FileCheck %s --check-prefix=OFF
@input8 = external local_unnamed_addr global i8, align 1
define dso_local i8 @Read8() local_unnamed_addr {
; DEFAULT-LABEL: Read8:
; DEFAULT: # %bb.0: # %entry
; DEFAULT-NEXT: pld r3, input8@got@pcrel(0), 1
; DEFAULT-NEXT: .Lpcrel:
; DEFAULT-NEXT: .reloc .Lpcrel-8,R_PPC64_PCREL_OPT,.-(.Lpcrel-8)
; DEFAULT-NEXT: lbz r3, 0(r3)
; DEFAULT-NEXT: blr
;
; ON-LABEL: Read8:
; ON: # %bb.0: # %entry
; ON-NEXT: pld r3, input8@got@pcrel(0), 1
; ON-NEXT: .Lpcrel:
; ON-NEXT: .reloc .Lpcrel-8,R_PPC64_PCREL_OPT,.-(.Lpcrel-8)
; ON-NEXT: lbz r3, 0(r3)
; ON-NEXT: blr
;
; OFF-LABEL: Read8:
; OFF: # %bb.0: # %entry
; OFF-NEXT: pld r3, input8@got@pcrel(0), 1
; OFF-NEXT: lbz r3, 0(r3)
; OFF-NEXT: blr
entry:
%0 = load i8, i8* @input8, align 1
ret i8 %0
}