[llvm-branch-commits] [llvm] [CodeGen][NPM] Update dominator tree and post dominator tree consistently (PR #173485)

[via llvm-branch-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-amdgpu

Author: Vikram Hegde (vikramRH)

<details>
<summary>Changes</summary>

These passes run "RenumberBlocks()" on Machine function which renders the dominator tree analyses in the cache stale (though passes may not change anything structurally). we need to update the block numbers in the cached analyses if we are to return PreservedAnalysis::all(). This is not an issue with legacy PM since none of these passes preserve dominator tree analyses anyway.

---
Full diff: https://github.com/llvm/llvm-project/pull/173485.diff


4 Files Affected:

- (modified) llvm/lib/CodeGen/BranchFolding.cpp (+11-2) 
- (modified) llvm/lib/CodeGen/BranchRelaxation.cpp (+10-1) 
- (modified) llvm/lib/CodeGen/MachineBlockPlacement.cpp (+7-4) 
- (modified) llvm/lib/Target/AMDGPU/SIPreEmitPeephole.cpp (+11-2) 


``````````diff
diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
index 0b212fb0beb20..7127fd556f733 100644
--- a/llvm/lib/CodeGen/BranchFolding.cpp
+++ b/llvm/lib/CodeGen/BranchFolding.cpp
@@ -28,6 +28,7 @@
 #include "llvm/CodeGen/MBFIWrapper.h"
 #include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
 #include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
+#include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineInstr.h"
@@ -35,6 +36,7 @@
 #include "llvm/CodeGen/MachineJumpTableInfo.h"
 #include "llvm/CodeGen/MachineLoopInfo.h"
 #include "llvm/CodeGen/MachineOperand.h"
+#include "llvm/CodeGen/MachinePostDominators.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/MachineSizeOpts.h"
 #include "llvm/CodeGen/TargetInstrInfo.h"
@@ -61,7 +63,6 @@
 #include <cstddef>
 #include <iterator>
 #include <numeric>
-
 using namespace llvm;
 
 #define DEBUG_TYPE "branch-folder"
@@ -135,12 +136,20 @@ PreservedAnalyses BranchFolderPass::run(MachineFunction &MF,
         "ProfileSummaryAnalysis is required for BranchFoldingPass", false);
 
   auto &MBFI = MFAM.getResult<MachineBlockFrequencyAnalysis>(MF);
+  auto *MDT = MFAM.getCachedResult<MachineDominatorTreeAnalysis>(MF);
+  auto *MPDT = MFAM.getCachedResult<MachinePostDominatorTreeAnalysis>(MF);
   MBFIWrapper MBBFreqInfo(MBFI);
   BranchFolder Folder(EnableTailMerge, /*CommonHoist=*/true, MBBFreqInfo, MBPI,
                       PSI);
   if (!Folder.OptimizeFunction(MF, MF.getSubtarget().getInstrInfo(),
-                               MF.getSubtarget().getRegisterInfo()))
+                               MF.getSubtarget().getRegisterInfo())) {
+    if (MDT)
+      MDT->updateBlockNumbers();
+    if (MPDT)
+      MPDT->updateBlockNumbers();
     return PreservedAnalyses::all();
+  }
+
   return getMachineFunctionPassPreservedAnalyses();
 }
 
diff --git a/llvm/lib/CodeGen/BranchRelaxation.cpp b/llvm/lib/CodeGen/BranchRelaxation.cpp
index fae952e888b4b..02a550f2e311a 100644
--- a/llvm/lib/CodeGen/BranchRelaxation.cpp
+++ b/llvm/lib/CodeGen/BranchRelaxation.cpp
@@ -11,9 +11,11 @@
 #include "llvm/ADT/Statistic.h"
 #include "llvm/CodeGen/LivePhysRegs.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachinePostDominators.h"
 #include "llvm/CodeGen/RegisterScavenging.h"
 #include "llvm/CodeGen/TargetInstrInfo.h"
 #include "llvm/CodeGen/TargetRegisterInfo.h"
@@ -769,8 +771,15 @@ bool BranchRelaxation::relaxBranchInstructions() {
 PreservedAnalyses
 BranchRelaxationPass::run(MachineFunction &MF,
                           MachineFunctionAnalysisManager &MFAM) {
-  if (!BranchRelaxation().run(MF))
+  auto *MDT = MFAM.getCachedResult<MachineDominatorTreeAnalysis>(MF);
+  auto *MPDT = MFAM.getCachedResult<MachinePostDominatorTreeAnalysis>(MF);
+  if (!BranchRelaxation().run(MF)) {
+    if (MDT)
+      MDT->updateBlockNumbers();
+    if (MPDT)
+      MPDT->updateBlockNumbers();
     return PreservedAnalyses::all();
+  }
 
   return getMachineFunctionPassPreservedAnalyses();
 }
diff --git a/llvm/lib/CodeGen/MachineBlockPlacement.cpp b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
index e9c75f0753f89..beff9a111b32c 100644
--- a/llvm/lib/CodeGen/MachineBlockPlacement.cpp
+++ b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
@@ -3541,19 +3541,22 @@ MachineBlockPlacementPass::run(MachineFunction &MF,
   auto *MPDT = MachineBlockPlacement::allowTailDupPlacement(MF)
                    ? &MFAM.getResult<MachinePostDominatorTreeAnalysis>(MF)
                    : nullptr;
+  auto *MDT = MFAM.getCachedResult<MachineDominatorTreeAnalysis>(MF);
   auto *PSI = MFAM.getResult<ModuleAnalysisManagerMachineFunctionProxy>(MF)
                   .getCachedResult<ProfileSummaryAnalysis>(
                       *MF.getFunction().getParent());
   if (!PSI)
     report_fatal_error("MachineBlockPlacement requires ProfileSummaryAnalysis",
                        false);
-
   MachineBlockPlacement MBP(MBPI, MLI, PSI, std::move(MBFI), MPDT,
                             AllowTailMerge);
-
-  if (!MBP.run(MF))
+  if (!MBP.run(MF)) {
+    if (MDT)
+      MDT->updateBlockNumbers();
+    if (MPDT)
+      MPDT->updateBlockNumbers();
     return PreservedAnalyses::all();
-
+  }
   return getMachineFunctionPassPreservedAnalyses();
 }
 
diff --git a/llvm/lib/Target/AMDGPU/SIPreEmitPeephole.cpp b/llvm/lib/Target/AMDGPU/SIPreEmitPeephole.cpp
index 8785968569d92..856b367a1f8f7 100644
--- a/llvm/lib/Target/AMDGPU/SIPreEmitPeephole.cpp
+++ b/llvm/lib/Target/AMDGPU/SIPreEmitPeephole.cpp
@@ -22,10 +22,11 @@
 #include "GCNSubtarget.h"
 #include "MCTargetDesc/AMDGPUMCTargetDesc.h"
 #include "llvm/ADT/SetVector.h"
+#include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachinePostDominators.h"
 #include "llvm/CodeGen/TargetSchedule.h"
 #include "llvm/Support/BranchProbability.h"
-
 using namespace llvm;
 
 #define DEBUG_TYPE "si-pre-emit-peephole"
@@ -705,8 +706,16 @@ MachineInstrBuilder SIPreEmitPeephole::createUnpackedMI(MachineInstr &I,
 PreservedAnalyses
 llvm::SIPreEmitPeepholePass::run(MachineFunction &MF,
                                  MachineFunctionAnalysisManager &MFAM) {
-  if (!SIPreEmitPeephole().run(MF))
+  auto *MDT = MFAM.getCachedResult<MachineDominatorTreeAnalysis>(MF);
+  auto *MPDT = MFAM.getCachedResult<MachinePostDominatorTreeAnalysis>(MF);
+
+  if (!SIPreEmitPeephole().run(MF)) {
+    if (MDT)
+      MDT->updateBlockNumbers();
+    if (MPDT)
+      MPDT->updateBlockNumbers();
     return PreservedAnalyses::all();
+  }
 
   return getMachineFunctionPassPreservedAnalyses();
 }

``````````

</details>


https://github.com/llvm/llvm-project/pull/173485