[llvm] r260427 - AMDGPU: Release the scavenged offset register during VGPR spill

Tom Stellard via llvm-commits llvm-commits at lists.llvm.org
Fri Feb 12 06:51:10 PST 2016


On Thu, Feb 11, 2016 at 09:13:17AM -0800, Hans Wennborg via llvm-commits wrote:
> Sounds good for 3.8 if Tom agrees.
> 

This is fine with me.

-Tom

> Thanks,
> Hans
> 
> On Thu, Feb 11, 2016 at 8:47 AM, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
> > Please consider this for the release branch(es).
> >
> > Thanks,
> > Nicolai
> >
> >
> > On 10.02.2016 15:13, Nicolai Haehnle via llvm-commits wrote:
> >>
> >> Author: nha
> >> Date: Wed Feb 10 14:13:58 2016
> >> New Revision: 260427
> >>
> >> URL: http://llvm.org/viewvc/llvm-project?rev=260427&view=rev
> >> Log:
> >> AMDGPU: Release the scavenged offset register during VGPR spill
> >>
> >> Summary:
> >> This fixes a crash where subsequent spills would be unable to scavenge
> >> a register. In particular, it fixes a crash in piglit's
> >> spec at glsl-1.50@execution at geometry@max-input-components (the test still
> >> has a shader that fails to compile because of too many SGPR spills, but
> >> at least it doesn't crash any more).
> >>
> >> This is a candidate for the release branch.
> >>
> >> Reviewers: arsenm, tstellarAMD
> >>
> >> Subscribers: qcolombet, arsenm
> >>
> >> Differential Revision: http://reviews.llvm.org/D16558
> >>
> >> Added:
> >>      llvm/trunk/test/CodeGen/AMDGPU/spill-scavenge-offset.ll
> >> Modified:
> >>      llvm/trunk/lib/Target/AMDGPU/SIRegisterInfo.cpp
> >>
> >> Modified: llvm/trunk/lib/Target/AMDGPU/SIRegisterInfo.cpp
> >> URL:
> >> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AMDGPU/SIRegisterInfo.cpp?rev=260427&r1=260426&r2=260427&view=diff
> >>
> >> ==============================================================================
> >> --- llvm/trunk/lib/Target/AMDGPU/SIRegisterInfo.cpp (original)
> >> +++ llvm/trunk/lib/Target/AMDGPU/SIRegisterInfo.cpp Wed Feb 10 14:13:58
> >> 2016
> >> @@ -234,6 +234,7 @@ void SIRegisterInfo::buildScratchLoadSto
> >>     bool IsLoad = TII->get(LoadStoreOp).mayLoad();
> >>
> >>     bool RanOutOfSGPRs = false;
> >> +  bool Scavenged = false;
> >>     unsigned SOffset = ScratchOffset;
> >>
> >>     unsigned NumSubRegs = getNumSubRegsForSpillOp(MI->getOpcode());
> >> @@ -244,6 +245,8 @@ void SIRegisterInfo::buildScratchLoadSto
> >>       if (SOffset == AMDGPU::NoRegister) {
> >>         RanOutOfSGPRs = true;
> >>         SOffset = AMDGPU::SGPR0;
> >> +    } else {
> >> +      Scavenged = true;
> >>       }
> >>       BuildMI(*MBB, MI, DL, TII->get(AMDGPU::S_ADD_U32), SOffset)
> >>               .addReg(ScratchOffset)
> >> @@ -259,10 +262,14 @@ void SIRegisterInfo::buildScratchLoadSto
> >>           getPhysRegSubReg(Value, &AMDGPU::VGPR_32RegClass, i) :
> >>           Value;
> >>
> >> +    unsigned SOffsetRegState = 0;
> >> +    if (i + 1 == e && Scavenged)
> >> +      SOffsetRegState |= RegState::Kill;
> >> +
> >>       BuildMI(*MBB, MI, DL, TII->get(LoadStoreOp))
> >>         .addReg(SubReg, getDefRegState(IsLoad))
> >>         .addReg(ScratchRsrcReg)
> >> -      .addReg(SOffset)
> >> +      .addReg(SOffset, SOffsetRegState)
> >>         .addImm(Offset)
> >>         .addImm(0) // glc
> >>         .addImm(0) // slc
> >>
> >> Added: llvm/trunk/test/CodeGen/AMDGPU/spill-scavenge-offset.ll
> >> URL:
> >> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AMDGPU/spill-scavenge-offset.ll?rev=260427&view=auto
> >>
> >> ==============================================================================
> >> --- llvm/trunk/test/CodeGen/AMDGPU/spill-scavenge-offset.ll (added)
> >> +++ llvm/trunk/test/CodeGen/AMDGPU/spill-scavenge-offset.ll Wed Feb 10
> >> 14:13:58 2016
> >> @@ -0,0 +1,33 @@
> >> +; RUN: llc -march=amdgcn -mcpu=verde < %s | FileCheck %s
> >> +; RUN: llc -march=amdgcn -mcpu=tonga < %s | FileCheck %s
> >> +
> >> +; When the offset of VGPR spills into scratch space gets too large, an
> >> additional SGPR
> >> +; is used to calculate the scratch load/store address. Make sure that
> >> this
> >> +; mechanism works even when many spills happen.
> >> +
> >> +; Just test that it compiles successfully.
> >> +; CHECK-LABEL: test
> >> +define void @test(<1280 x i32> addrspace(1)* %out, <1280 x i32>
> >> addrspace(1)* %in,
> >> +                  <96 x i32> addrspace(1)* %sdata_out, <96 x i32>
> >> %sdata_in) {
> >> +entry:
> >> +  %tid = call i32 @llvm.SI.tid() nounwind readnone
> >> +
> >> +  %aptr = getelementptr <1280 x i32>, <1280 x i32> addrspace(1)* %in, i32
> >> %tid
> >> +  %a = load <1280 x i32>, <1280 x i32> addrspace(1)* %aptr
> >> +
> >> +; mark most VGPR registers as used to increase register pressure
> >> +  call void asm sideeffect "",
> >> "~{VGPR4},~{VGPR8},~{VGPR12},~{VGPR16},~{VGPR20},~{VGPR24},~{VGPR28},~{VGPR32}"
> >> ()
> >> +  call void asm sideeffect "",
> >> "~{VGPR36},~{VGPR40},~{VGPR44},~{VGPR48},~{VGPR52},~{VGPR56},~{VGPR60},~{VGPR64}"
> >> ()
> >> +  call void asm sideeffect "",
> >> "~{VGPR68},~{VGPR72},~{VGPR76},~{VGPR80},~{VGPR84},~{VGPR88},~{VGPR92},~{VGPR96}"
> >> ()
> >> +  call void asm sideeffect "",
> >> "~{VGPR100},~{VGPR104},~{VGPR108},~{VGPR112},~{VGPR116},~{VGPR120},~{VGPR124},~{VGPR128}"
> >> ()
> >> +  call void asm sideeffect "",
> >> "~{VGPR132},~{VGPR136},~{VGPR140},~{VGPR144},~{VGPR148},~{VGPR152},~{VGPR156},~{VGPR160}"
> >> ()
> >> +  call void asm sideeffect "",
> >> "~{VGPR164},~{VGPR168},~{VGPR172},~{VGPR176},~{VGPR180},~{VGPR184},~{VGPR188},~{VGPR192}"
> >> ()
> >> +  call void asm sideeffect "",
> >> "~{VGPR196},~{VGPR200},~{VGPR204},~{VGPR208},~{VGPR212},~{VGPR216},~{VGPR220},~{VGPR224}"
> >> ()
> >> +
> >> +  %outptr = getelementptr <1280 x i32>, <1280 x i32> addrspace(1)* %in,
> >> i32 %tid
> >> +  store <1280 x i32> %a, <1280 x i32> addrspace(1)* %outptr
> >> +
> >> +  ret void
> >> +}
> >> +
> >> +declare i32 @llvm.SI.tid() nounwind readnone
> >>
> >>
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> >
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