[PATCH] D124797: [memprof] Only insert dynamic shadow load when needed
Teresa Johnson via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon May 2 12:41:47 PDT 2022
tejohnson created this revision.
tejohnson added a reviewer: snehasish.
Herald added a subscriber: hiraditya.
Herald added a project: All.
tejohnson requested review of this revision.
Herald added a project: LLVM.
We don't need to insert a load of the dynamic shadow address when there
are interesting memory accesses to profile.
Split out of D124703 <https://reviews.llvm.org/D124703>.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D124797
Files:
llvm/lib/Transforms/Instrumentation/MemProfiler.cpp
llvm/test/Instrumentation/HeapProfiler/no-instrumentation.ll
Index: llvm/test/Instrumentation/HeapProfiler/no-instrumentation.ll
===================================================================
--- /dev/null
+++ llvm/test/Instrumentation/HeapProfiler/no-instrumentation.ll
@@ -0,0 +1,17 @@
+;; Test that we don't add any instrumentation code to functions without
+;; interesting memory accesses.
+;
+; RUN: opt < %s -passes='function(memprof),module(memprof-module)' -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @_Z3foov() {
+entry:
+ ret void
+}
+
+;; We should not add any instrumentation related code
+; CHECK: define void @_Z3foov
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret void
Index: llvm/lib/Transforms/Instrumentation/MemProfiler.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/MemProfiler.cpp
+++ llvm/lib/Transforms/Instrumentation/MemProfiler.cpp
@@ -633,8 +633,6 @@
initializeCallbacks(*F.getParent());
- FunctionModified |= insertDynamicShadowAtFunctionEntry(F);
-
SmallVector<Instruction *, 16> ToInstrument;
// Fill the set of memory operations to instrument.
@@ -645,6 +643,15 @@
}
}
+ if (ToInstrument.empty()) {
+ LLVM_DEBUG(dbgs() << "MEMPROF done instrumenting: " << FunctionModified
+ << " " << F << "\n");
+
+ return FunctionModified;
+ }
+
+ FunctionModified |= insertDynamicShadowAtFunctionEntry(F);
+
int NumInstrumented = 0;
for (auto *Inst : ToInstrument) {
if (ClDebugMin < 0 || ClDebugMax < 0 ||
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