[llvm] [AMDGPU] Remove dom tree requirements from SIWholeQuadMode pass (PR #71012)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-amdgpu

Author: Carl Ritson (perlfu)

<details>
<summary>Changes</summary>

SIWholeQuadMode preserves dominator and post dominator trees, but does not require them.

---
Full diff: https://github.com/llvm/llvm-project/pull/71012.diff


2 Files Affected:

- (modified) llvm/lib/Target/AMDGPU/SIWholeQuadMode.cpp (+2-4) 
- (modified) llvm/test/CodeGen/AMDGPU/llc-pipeline.ll (-5) 


``````````diff
diff --git a/llvm/lib/Target/AMDGPU/SIWholeQuadMode.cpp b/llvm/lib/Target/AMDGPU/SIWholeQuadMode.cpp
index 3143d437e37091b..d1d828bfbdb70da 100644
--- a/llvm/lib/Target/AMDGPU/SIWholeQuadMode.cpp
+++ b/llvm/lib/Target/AMDGPU/SIWholeQuadMode.cpp
@@ -238,9 +238,7 @@ class SIWholeQuadMode : public MachineFunctionPass {
     AU.addRequired<LiveIntervals>();
     AU.addPreserved<SlotIndexes>();
     AU.addPreserved<LiveIntervals>();
-    AU.addRequired<MachineDominatorTree>();
     AU.addPreserved<MachineDominatorTree>();
-    AU.addRequired<MachinePostDominatorTree>();
     AU.addPreserved<MachinePostDominatorTree>();
     MachineFunctionPass::getAnalysisUsage(AU);
   }
@@ -1594,8 +1592,8 @@ bool SIWholeQuadMode::runOnMachineFunction(MachineFunction &MF) {
   TRI = &TII->getRegisterInfo();
   MRI = &MF.getRegInfo();
   LIS = &getAnalysis<LiveIntervals>();
-  MDT = &getAnalysis<MachineDominatorTree>();
-  PDT = &getAnalysis<MachinePostDominatorTree>();
+  MDT = getAnalysisIfAvailable<MachineDominatorTree>();
+  PDT = getAnalysisIfAvailable<MachinePostDominatorTree>();
 
   if (ST->isWave32()) {
     AndOpc = AMDGPU::S_AND_B32;
diff --git a/llvm/test/CodeGen/AMDGPU/llc-pipeline.ll b/llvm/test/CodeGen/AMDGPU/llc-pipeline.ll
index bf2f6e983b529f8..5e922f608c1daa7 100644
--- a/llvm/test/CodeGen/AMDGPU/llc-pipeline.ll
+++ b/llvm/test/CodeGen/AMDGPU/llc-pipeline.ll
@@ -105,7 +105,6 @@
 ; GCN-O0-NEXT:        MachineDominator Tree Construction
 ; GCN-O0-NEXT:        Slot index numbering
 ; GCN-O0-NEXT:        Live Interval Analysis
-; GCN-O0-NEXT:        MachinePostDominator Tree Construction
 ; GCN-O0-NEXT:        SI Whole Quad Mode
 ; GCN-O0-NEXT:        Virtual Register Map
 ; GCN-O0-NEXT:        Live Register Matrix
@@ -334,7 +333,6 @@
 ; GCN-O1-NEXT:        Register Coalescer
 ; GCN-O1-NEXT:        Rename Disconnected Subregister Components
 ; GCN-O1-NEXT:        Machine Instruction Scheduler
-; GCN-O1-NEXT:        MachinePostDominator Tree Construction
 ; GCN-O1-NEXT:        SI Whole Quad Mode
 ; GCN-O1-NEXT:        Virtual Register Map
 ; GCN-O1-NEXT:        Live Register Matrix
@@ -626,7 +624,6 @@
 ; GCN-O1-OPTS-NEXT:        Rename Disconnected Subregister Components
 ; GCN-O1-OPTS-NEXT:        AMDGPU Pre-RA optimizations
 ; GCN-O1-OPTS-NEXT:        Machine Instruction Scheduler
-; GCN-O1-OPTS-NEXT:        MachinePostDominator Tree Construction
 ; GCN-O1-OPTS-NEXT:        SI Whole Quad Mode
 ; GCN-O1-OPTS-NEXT:        Virtual Register Map
 ; GCN-O1-OPTS-NEXT:        Live Register Matrix
@@ -929,7 +926,6 @@
 ; GCN-O2-NEXT:        Rename Disconnected Subregister Components
 ; GCN-O2-NEXT:        AMDGPU Pre-RA optimizations
 ; GCN-O2-NEXT:        Machine Instruction Scheduler
-; GCN-O2-NEXT:        MachinePostDominator Tree Construction
 ; GCN-O2-NEXT:        SI Whole Quad Mode
 ; GCN-O2-NEXT:        Virtual Register Map
 ; GCN-O2-NEXT:        Live Register Matrix
@@ -1245,7 +1241,6 @@
 ; GCN-O3-NEXT:        Rename Disconnected Subregister Components
 ; GCN-O3-NEXT:        AMDGPU Pre-RA optimizations
 ; GCN-O3-NEXT:        Machine Instruction Scheduler
-; GCN-O3-NEXT:        MachinePostDominator Tree Construction
 ; GCN-O3-NEXT:        SI Whole Quad Mode
 ; GCN-O3-NEXT:        Virtual Register Map
 ; GCN-O3-NEXT:        Live Register Matrix

``````````

</details>


https://github.com/llvm/llvm-project/pull/71012