[llvm] r312635 - AMDGPU: Make worst-case assumption about the wait states in inline assembly
Nicolai Haehnle via llvm-commits
llvm-commits at lists.llvm.org
Wed Sep 6 06:50:13 PDT 2017
Author: nha
Date: Wed Sep 6 06:50:13 2017
New Revision: 312635
URL: http://llvm.org/viewvc/llvm-project?rev=312635&view=rev
Log:
AMDGPU: Make worst-case assumption about the wait states in inline assembly
Summary:
Mesa still uses a hack where empty inline assembly is used as a kind of
optimization barrier. This exposed a problem where not enough wait states
were inserted, because the hazard recognizer implicitly assumed that each
inline assembly "instruction" has at least one wait state.
Reviewers: arsenm
Subscribers: kzhuravl, wdng, yaxunl, dstuttard, tpr, llvm-commits, t-tye
Differential Revision: https://reviews.llvm.org/D37205
Modified:
llvm/trunk/lib/Target/AMDGPU/GCNHazardRecognizer.cpp
llvm/trunk/test/CodeGen/AMDGPU/hazard.mir
Modified: llvm/trunk/lib/Target/AMDGPU/GCNHazardRecognizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AMDGPU/GCNHazardRecognizer.cpp?rev=312635&r1=312634&r2=312635&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AMDGPU/GCNHazardRecognizer.cpp (original)
+++ llvm/trunk/lib/Target/AMDGPU/GCNHazardRecognizer.cpp Wed Sep 6 06:50:13 2017
@@ -225,7 +225,8 @@ int GCNHazardRecognizer::getWaitStatesSi
return WaitStates;
unsigned Opcode = MI->getOpcode();
- if (Opcode == AMDGPU::DBG_VALUE || Opcode == AMDGPU::IMPLICIT_DEF)
+ if (Opcode == AMDGPU::DBG_VALUE || Opcode == AMDGPU::IMPLICIT_DEF ||
+ Opcode == AMDGPU::INLINEASM)
continue;
}
++WaitStates;
Modified: llvm/trunk/test/CodeGen/AMDGPU/hazard.mir
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AMDGPU/hazard.mir?rev=312635&r1=312634&r2=312635&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AMDGPU/hazard.mir (original)
+++ llvm/trunk/test/CodeGen/AMDGPU/hazard.mir Wed Sep 6 06:50:13 2017
@@ -1,6 +1,7 @@
# RUN: llc -march=amdgcn -mcpu=tonga -verify-machineinstrs -run-pass post-RA-hazard-rec %s -o - | FileCheck -check-prefix=GCN -check-prefix=VI %s
# RUN: llc -march=amdgcn -mcpu=gfx900 -verify-machineinstrs -run-pass post-RA-hazard-rec %s -o - | FileCheck -check-prefix=GCN -check-prefix=GFX9 %s
+# GCN-LABEL: name: hazard_implicit_def
# GCN: bb.0.entry:
# GCN: %m0 = S_MOV_B32
# GFX9: S_NOP 0
@@ -29,3 +30,31 @@ body: |
SI_RETURN_TO_EPILOG killed %vgpr5, killed %vgpr0
...
+
+# GCN-LABEL: name: hazard_inlineasm
+# GCN: bb.0.entry:
+# GCN: %m0 = S_MOV_B32
+# GFX9: S_NOP 0
+# VI-NOT: S_NOP_0
+# GCN: V_INTERP_P1_F32
+---
+name: hazard_inlineasm
+alignment: 0
+exposesReturnsTwice: false
+legalized: false
+regBankSelected: false
+selected: false
+tracksRegLiveness: true
+registers:
+liveins:
+ - { reg: '%sgpr7', virtual-reg: '' }
+ - { reg: '%vgpr4', virtual-reg: '' }
+body: |
+ bb.0.entry:
+ liveins: %sgpr7, %vgpr4
+
+ %m0 = S_MOV_B32 killed %sgpr7
+ INLINEASM $"; no-op", 1, 327690, def %vgpr5
+ %vgpr0 = V_INTERP_P1_F32 killed %vgpr4, 0, 0, implicit %m0, implicit %exec
+ SI_RETURN_TO_EPILOG killed %vgpr5, killed %vgpr0
+...
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