[PATCH] D44666: [XRay] Lazily compute MachineLoopInfo instead of requiring it.
Michael Zolotukhin via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon Mar 19 17:48:00 PDT 2018
mzolotukhin created this revision.
mzolotukhin added reviewers: dberris, kubamracek.
Herald added a subscriber: hiraditya.
Currently X-Ray Instrumentation pass has a dependency on MachineLoopInfo
(and thus on MachineDominatorTree as well) and we have to compute them
even if X-Ray is not used. This patch changes it to a lazy computation
to save compile time by avoiding these redundant computations.
Repository:
rL LLVM
https://reviews.llvm.org/D44666
Files:
llvm/lib/CodeGen/XRayInstrumentation.cpp
llvm/test/CodeGen/X86/O0-pipeline.ll
Index: llvm/test/CodeGen/X86/O0-pipeline.ll
===================================================================
--- llvm/test/CodeGen/X86/O0-pipeline.ll
+++ llvm/test/CodeGen/X86/O0-pipeline.ll
@@ -55,8 +55,6 @@
; CHECK-NEXT: StackMap Liveness Analysis
; CHECK-NEXT: Live DEBUG_VALUE analysis
; CHECK-NEXT: Insert fentry calls
-; CHECK-NEXT: MachineDominator Tree Construction
-; CHECK-NEXT: Machine Natural Loop Construction
; CHECK-NEXT: Insert XRay ops
; CHECK-NEXT: Implement the 'patchable-function' attribute
; CHECK-NEXT: X86 Retpoline Thunks
Index: llvm/lib/CodeGen/XRayInstrumentation.cpp
===================================================================
--- llvm/lib/CodeGen/XRayInstrumentation.cpp
+++ llvm/lib/CodeGen/XRayInstrumentation.cpp
@@ -52,7 +52,6 @@
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
- AU.addRequired<MachineLoopInfo>();
AU.addPreserved<MachineLoopInfo>();
AU.addPreserved<MachineDominatorTree>();
MachineFunctionPass::getAnalysisUsage(AU);
@@ -160,11 +159,26 @@
for (const auto &MBB : MF)
MICount += MBB.size();
+ // Get MachineDominatorTree or compute it on the fly if it's unavailable
+ auto *MDT = getAnalysisIfAvailable<MachineDominatorTree>();
+ MachineDominatorTree ComputedMDT;
+ if (!MDT) {
+ ComputedMDT.getBase().recalculate(MF);
+ MDT = &ComputedMDT;
+ }
+
+ // Get MachineLoopInfo or compute it on the fly if it's unavailable
+ auto *MLI = getAnalysisIfAvailable<MachineLoopInfo>();
+ MachineLoopInfo ComputedMLI;
+ if (!MLI) {
+ ComputedMLI.getBase().analyze(MDT->getBase());
+ MLI = &ComputedMLI;
+ }
+
// Check if we have a loop.
// FIXME: Maybe make this smarter, and see whether the loops are dependent
// on inputs or side-effects?
- MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
- if (MLI.empty() && MICount < XRayThreshold)
+ if (MLI->empty() && MICount < XRayThreshold)
return false; // Function is too small and has no loops.
}
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D44666.139060.patch
Type: text/x-patch
Size: 2112 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180320/aaa09414/attachment.bin>
More information about the llvm-commits
mailing list