[PATCH] D40822: AMDGPU: Fix infinite loop with dbg_value
Matt Arsenault via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon Dec 4 19:01:11 PST 2017
arsenm created this revision.
Herald added subscribers: t-tye, tpr, dstuttard, yaxunl, nhaehnle, wdng, kzhuravl.
Surprisingly SIOptimizeExecMaskingPreRA can infinite loop
in some case with DBG_VALUE. Most tests using dbg_value are
run at -O0, so don't run this pass. This seems to only
happen when the value argument is undef.
https://reviews.llvm.org/D40822
Files:
lib/Target/AMDGPU/SIOptimizeExecMaskingPreRA.cpp
test/CodeGen/AMDGPU/llvm.dbg.value.ll
Index: test/CodeGen/AMDGPU/llvm.dbg.value.ll
===================================================================
--- test/CodeGen/AMDGPU/llvm.dbg.value.ll
+++ test/CodeGen/AMDGPU/llvm.dbg.value.ll
@@ -1,22 +1,37 @@
-; RUN: llc -O0 -march=amdgcn -mtriple=amdgcn-unknown-amdhsa -verify-machineinstrs -mattr=-flat-for-global < %s | FileCheck %s
+; RUN: llc -O0 -march=amdgcn -mtriple=amdgcn-unknown-amdhsa -verify-machineinstrs < %s | FileCheck -check-prefixes=GCN,NOOPT %s
+; RUN: llc -march=amdgcn -mtriple=amdgcn-unknown-amdhsa -verify-machineinstrs < %s | FileCheck -check-prefixes=GCN,OPT %s
-; CHECK-LABEL: {{^}}test_debug_value:
-; CHECK: s_load_dwordx2 s[4:5]
+; GCN-LABEL: {{^}}test_debug_value:
+; NOOPT: s_load_dwordx2 s[4:5]
; FIXME: Why is the SGPR4_SGPR5 reference being removed from DBG_VALUE?
-; CHECK: ; kill: %sgpr4_sgpr5<def> %sgpr4_sgpr5<kill>
-; CHECK-NEXT: ;DEBUG_VALUE: test_debug_value:globalptr_arg <- undef
+; NOOPT: ; kill: %sgpr8_sgpr9<def> %sgpr4_sgpr5<kill>
+; NOOPT-NEXT: ;DEBUG_VALUE: test_debug_value:globalptr_arg <- undef
-; CHECK: buffer_store_dword
-; CHECK: s_endpgm
+; GCN: flat_store_dword
+; GCN: s_endpgm
define amdgpu_kernel void @test_debug_value(i32 addrspace(1)* nocapture %globalptr_arg) #0 !dbg !4 {
entry:
- tail call void @llvm.dbg.value(metadata i32 addrspace(1)* %globalptr_arg, i64 0, metadata !10, metadata !13), !dbg !14
+ tail call void @llvm.dbg.value(metadata i32 addrspace(1)* %globalptr_arg, metadata !10, metadata !13), !dbg !14
store i32 123, i32 addrspace(1)* %globalptr_arg, align 4
ret void
}
-declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #1
+; Check for infinite loop in some cases with dbg_value in
+; SIOptimizeExecMaskingPreRA (somehow related to undef argument).
+
+; GCN-LABEL: {{^}}only_undef_dbg_value:
+; NOOPT: ;DEBUG_VALUE: test_debug_value:globalptr_arg <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef] undef
+; NOOPT-NEXT: s_endpgm
+
+; OPT: s_endpgm
+define amdgpu_kernel void @only_undef_dbg_value() #1 {
+bb:
+ call void @llvm.dbg.value(metadata <4 x float> undef, metadata !10, metadata !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef)) #2, !dbg !14
+ ret void
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata) #1
attributes #0 = { nounwind }
attributes #1 = { nounwind readnone }
Index: lib/Target/AMDGPU/SIOptimizeExecMaskingPreRA.cpp
===================================================================
--- lib/Target/AMDGPU/SIOptimizeExecMaskingPreRA.cpp
+++ lib/Target/AMDGPU/SIOptimizeExecMaskingPreRA.cpp
@@ -134,8 +134,11 @@
}
while (I != E) {
- if (I->isDebugValue())
+ if (I->isDebugValue()) {
+ I = std::next(I);
continue;
+ }
+
if (I->mayStore() || I->isBarrier() || I->isCall() ||
I->hasUnmodeledSideEffects() || I->hasOrderedMemoryRef())
break;
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