[AMDGPU] detect WaW hazards when moving/merging load/store instructions
Summary:
In order to combine memory operations efficiently, the load/store
optimizer might move some instructions around. It's usually safe
to move instructions down past the merged instruction because the
pass checks if memory operations can be re-ordered.
Though, the current logic doesn't handle Write-after-Write hazards.
This fixes a reflection issue with Monster Hunter World and DXVK.
v2: - rebased on top of master
- clean up the test case
- handle WaW hazards correctly
Bugzilla: https://bugs.llvm.org/show_bug.cgi?id=40130
Original patch by Samuel Pitoiset.
Reviewers: tpr, arsenm, nhaehnle
Reviewed By: nhaehnle
Subscribers: ronlieb, arsenm, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye
Differential Revision: https://reviews.llvm.org/D61313
llvm-svn: 361008
diff --git a/llvm/lib/Target/AMDGPU/SILoadStoreOptimizer.cpp b/llvm/lib/Target/AMDGPU/SILoadStoreOptimizer.cpp
index b7541e0..461f7b2 100644
--- a/llvm/lib/Target/AMDGPU/SILoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/AMDGPU/SILoadStoreOptimizer.cpp
@@ -281,6 +281,7 @@
// registers are in SSA form.
if (Use.isReg() &&
((Use.readsReg() && RegDefs.count(Use.getReg())) ||
+ (Use.isDef() && RegDefs.count(Use.getReg())) ||
(Use.isDef() && TargetRegisterInfo::isPhysicalRegister(Use.getReg()) &&
PhysRegUses.count(Use.getReg())))) {
Insts.push_back(&MI);