From 25e2616626caafb896517e18cd8aa724fba2b200 Mon Sep 17 00:00:00 2001
From: Tom Stellard <thomas.stellard@amd.com>
Date: Tue, 29 Nov 2016 03:41:28 +0000
Subject: [PATCH] Merging r280589:
------------------------------------------------------------------------
r280589 | nhaehnle | 2016-09-03 05:26:32 -0700 (Sat, 03 Sep 2016) | 19 lines
AMDGPU: Fix an interaction between WQM and polygon stippling
Summary:
This fixes a rare bug in polygon stippling with non-monolithic pixel shaders.
The underlying problem is as follows: the prolog part contains the polygon
stippling sequence, i.e. a kill. The main part then enables WQM based on the
_reduced_ exec mask, effectively undoing most of the polygon stippling.
Since we cannot know whether polygon stippling will be used, the main part
of a non-monolithic shader must always return to exact mode to fix this
problem.
Reviewers: arsenm, tstellarAMD, mareko
Subscribers: arsenm, llvm-commits, kzhuravl
Differential Revision: https://reviews.llvm.org/D23131
------------------------------------------------------------------------
git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_39@288105 91177308-0d34-0410-b5e6-96231b3b80d8
---
lib/Target/AMDGPU/SIInstructions.td | 1 +
lib/Target/AMDGPU/SIWholeQuadMode.cpp | 7 -----
test/CodeGen/AMDGPU/wqm.ll | 49 ++++++++++++++++++++++++++++++++---
3 files changed, 46 insertions(+), 11 deletions(-)
diff --git a/lib/Target/AMDGPU/SIInstructions.td b/lib/Target/AMDGPU/SIInstructions.td
index 18b7d5d..dde5f2f 100644
--- a/lib/Target/AMDGPU/SIInstructions.td
+++ b/lib/Target/AMDGPU/SIInstructions.td
@@ -2029,6 +2029,7 @@ def SI_RETURN : PseudoInstSI <
let hasSideEffects = 1;
let SALU = 1;
let hasNoSchedulingInfo = 1;
+ let DisableWQM = 1;
}
let Uses = [EXEC], Defs = [EXEC, VCC, M0],
diff --git a/lib/Target/AMDGPU/SIWholeQuadMode.cpp b/lib/Target/AMDGPU/SIWholeQuadMode.cpp
index b200c15..1534d58 100644
--- a/lib/Target/AMDGPU/SIWholeQuadMode.cpp
+++ b/lib/Target/AMDGPU/SIWholeQuadMode.cpp
@@ -219,13 +219,6 @@ char SIWholeQuadMode::scanInstructions(MachineFunction &MF,
markInstruction(MI, Flags, Worklist);
GlobalFlags |= Flags;
}
-
- if (WQMOutputs && MBB.succ_empty()) {
- // This is a prolog shader. Make sure we go back to exact mode at the end.
- Blocks[&MBB].OutNeeds = StateExact;
- Worklist.push_back(&MBB);
- GlobalFlags |= StateExact;
- }
}
return GlobalFlags;
diff --git a/test/CodeGen/AMDGPU/wqm.ll b/test/CodeGen/AMDGPU/wqm.ll
index 809a7ba..41e4264 100644
--- a/test/CodeGen/AMDGPU/wqm.ll
+++ b/test/CodeGen/AMDGPU/wqm.ll
@@ -17,17 +17,18 @@ main_body:
;CHECK-LABEL: {{^}}test2:
;CHECK-NEXT: ; %main_body
;CHECK-NEXT: s_wqm_b64 exec, exec
-;CHECK: image_sample
;CHECK-NOT: exec
-;CHECK: _load_dword v0,
-define amdgpu_ps float @test2(<8 x i32> inreg %rsrc, <4 x i32> inreg %sampler, float addrspace(1)* inreg %ptr, <4 x i32> %c) {
+define amdgpu_ps void @test2(<8 x i32> inreg %rsrc, <4 x i32> inreg %sampler, float addrspace(1)* inreg %ptr, <4 x i32> %c) {
main_body:
%c.1 = call <4 x float> @llvm.SI.image.sample.v4i32(<4 x i32> %c, <8 x i32> %rsrc, <4 x i32> %sampler, i32 15, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0)
%c.2 = bitcast <4 x float> %c.1 to <4 x i32>
%c.3 = extractelement <4 x i32> %c.2, i32 0
%gep = getelementptr float, float addrspace(1)* %ptr, i32 %c.3
%data = load float, float addrspace(1)* %gep
- ret float %data
+
+ call void @llvm.SI.export(i32 15, i32 1, i32 1, i32 0, i32 1, float %data, float undef, float undef, float undef)
+
+ ret void
}
; ... but disabled for stores (and, in this simple case, not re-enabled).
@@ -414,6 +415,46 @@ entry:
ret void
}
+; Must return to exact at the end of a non-void returning shader,
+; otherwise the EXEC mask exported by the epilog will be wrong. This is true
+; even if the shader has no kills, because a kill could have happened in a
+; previous shader fragment.
+;
+; CHECK-LABEL: {{^}}test_nonvoid_return:
+; CHECK: s_mov_b64 [[LIVE:s\[[0-9]+:[0-9]+\]]], exec
+; CHECK: s_wqm_b64 exec, exec
+;
+; CHECK: s_and_b64 exec, exec, [[LIVE]]
+; CHECK-NOT: exec
+define amdgpu_ps <4 x float> @test_nonvoid_return() nounwind {
+ %tex = call <4 x float> @llvm.SI.image.sample.v4i32(<4 x i32> undef, <8 x i32> undef, <4 x i32> undef, i32 15, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0)
+ %tex.i = bitcast <4 x float> %tex to <4 x i32>
+ %dtex = call <4 x float> @llvm.SI.image.sample.v4i32(<4 x i32> %tex.i, <8 x i32> undef, <4 x i32> undef, i32 15, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0)
+ ret <4 x float> %dtex
+}
+
+; CHECK-LABEL: {{^}}test_nonvoid_return_unreachable:
+; CHECK: s_mov_b64 [[LIVE:s\[[0-9]+:[0-9]+\]]], exec
+; CHECK: s_wqm_b64 exec, exec
+;
+; CHECK: s_and_b64 exec, exec, [[LIVE]]
+; CHECK-NOT: exec
+define amdgpu_ps <4 x float> @test_nonvoid_return_unreachable(i32 inreg %c) nounwind {
+entry:
+ %tex = call <4 x float> @llvm.SI.image.sample.v4i32(<4 x i32> undef, <8 x i32> undef, <4 x i32> undef, i32 15, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0)
+ %tex.i = bitcast <4 x float> %tex to <4 x i32>
+ %dtex = call <4 x float> @llvm.SI.image.sample.v4i32(<4 x i32> %tex.i, <8 x i32> undef, <4 x i32> undef, i32 15, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0)
+
+ %cc = icmp sgt i32 %c, 0
+ br i1 %cc, label %if, label %else
+
+if:
+ store volatile <4 x float> %dtex, <4 x float>* undef
+ unreachable
+
+else:
+ ret <4 x float> %dtex
+}
declare void @llvm.amdgcn.image.store.v4i32(<4 x float>, <4 x i32>, <8 x i32>, i32, i1, i1, i1, i1) #1
declare void @llvm.amdgcn.buffer.store.f32(float, <4 x i32>, i32, i32, i1, i1) #1