[PATCH] D144483: [Assignment Tracking] Choose better passes for RemoveRedundantDbgInstrs call

[Orlando Cazalet-Hyams via Phabricator via llvm-commits]

Orlando created this revision.
Orlando added reviewers: jmorse, StephenTozer, scott.linder.
Orlando added a project: debug-info.
Herald added a subscriber: hiraditya.
Herald added a project: All.
Orlando requested review of this revision.
Herald added subscribers: llvm-commits, pcwang-thead.
Herald added a project: LLVM.

Enabling assignment tracking without this patch, a significant amount of additional compiler run time comes from the RemoveRedundantDbgInstrs call in InstCombine. This patch reduces compiler run time by choosing better places to call RemoveRedundantDbgInstrs.

In non-assignment-tracking builds, RemoveRedundantDbgInstrs is called by InstCombine if LowerDbgDeclare makes a change (i.e. it is _sometimes_ called). In assignment tracking builds LowerDbgDeclare doesn't do anything. We still need to clean up redundant intrinsics to avoid a large performance hit due to the number of instructions, so the current approach is to have InstCombine _always_ call RemoveRedundantDbgInstrs.

Instrumenting the compiler to run RemoveRedundantDbgInstrs after every pass and dump the numbers and building CTMark/tramp3d-v4 indicates that SROA and LoopVectorize give us a bigger bang (number removed) for buck (times pass is run).

The compile time tracker reports that this patch reduces the number of instructions retired building CTMark projects by an average of 1.1%.


https://reviews.llvm.org/D144483

Files:
  llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
  llvm/lib/Transforms/Scalar/SROA.cpp
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp


Index: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -98,6 +98,7 @@
 #include "llvm/IR/Constant.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/DebugLoc.h"
 #include "llvm/IR/DerivedTypes.h"
@@ -10554,6 +10555,11 @@
       return PreservedAnalyses::all();
     PreservedAnalyses PA;
 
+    if (isAssignmentTrackingEnabled(*F.getParent())) {
+      for (auto &BB : F)
+      RemoveRedundantDbgInstrs(&BB);
+    }
+
     // We currently do not preserve loopinfo/dominator analyses with outer loop
     // vectorization. Until this is addressed, mark these analyses as preserved
     // only for non-VPlan-native path.
Index: llvm/lib/Transforms/Scalar/SROA.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/SROA.cpp
+++ llvm/lib/Transforms/Scalar/SROA.cpp
@@ -5045,6 +5045,11 @@
   if (!Changed)
     return PreservedAnalyses::all();
 
+  if (isAssignmentTrackingEnabled(*F.getParent())) {
+    for (auto &BB : F)
+      RemoveRedundantDbgInstrs(&BB);
+  }
+
   PreservedAnalyses PA;
   if (!CFGChanged)
     PA.preserveSet<CFGAnalyses>();
Index: llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -4601,13 +4601,6 @@
   bool MadeIRChange = false;
   if (ShouldLowerDbgDeclare)
     MadeIRChange = LowerDbgDeclare(F);
-  // LowerDbgDeclare calls RemoveRedundantDbgInstrs, but LowerDbgDeclare will
-  // almost never return true when running an assignment tracking build. Take
-  // this opportunity to do some clean up for assignment tracking builds too.
-  if (!MadeIRChange && isAssignmentTrackingEnabled(*F.getParent())) {
-    for (auto &BB : F)
-      RemoveRedundantDbgInstrs(&BB);
-  }
 
   // Iterate while there is work to do.
   unsigned Iteration = 0;


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D144483.499152.patch
Type: text/x-patch
Size: 2201 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20230221/b3ce8ab8/attachment.bin>