From 5d95513e1d70b6d056c93c967c336b9658ac395b Mon Sep 17 00:00:00 2001
From: Jakob Botsch Nielsen <jakob.botsch.nielsen@gmail.com>
Date: Thu, 20 Jun 2024 14:35:52 +0200
Subject: [PATCH] JIT: Specialize `fgFindJumpTargets`
This specializes `fgFindJumpTargets` based on whether we are making
inline observations or not. This function has a lot of conditional logic
based on this property, but it is always going to be false in MinOpts,
so this allows the native compiler to optimize the function much better
(and avoids all the conditionals).
Using the VS profiler shows that the relative CPU time spent in the
function goes from 0.98% to 0.47% for the MinOpts contexts in
benchmarks.run_pgo.windows.x64.
---
src/coreclr/jit/compiler.h | 1 +
src/coreclr/jit/fgbasic.cpp | 28 +++++++++++++++++++---------
2 files changed, 20 insertions(+), 9 deletions(-)
diff --git a/src/coreclr/jit/compiler.h b/src/coreclr/jit/compiler.h
index 7bf00c5cc84d62..34334c6f2eaac5 100644
--- a/src/coreclr/jit/compiler.h
+++ b/src/coreclr/jit/compiler.h
@@ -6315,6 +6315,7 @@ class Compiler
bool fgMayExplicitTailCall();
+ template<bool makeInlineObservations>
void fgFindJumpTargets(const BYTE* codeAddr, IL_OFFSET codeSize, FixedBitVect* jumpTarget);
void fgMarkBackwardJump(BasicBlock* startBlock, BasicBlock* endBlock);
diff --git a/src/coreclr/jit/fgbasic.cpp b/src/coreclr/jit/fgbasic.cpp
index da31f325424e40..f2c0f458c10505 100644
--- a/src/coreclr/jit/fgbasic.cpp
+++ b/src/coreclr/jit/fgbasic.cpp
@@ -1064,13 +1064,16 @@ class FgStack
//------------------------------------------------------------------------
// fgFindJumpTargets: walk the IL stream, determining jump target offsets
//
+// Type arguments:
+// makeInlineObservations - whether or not to record inline observations about the method
+//
// Arguments:
// codeAddr - base address of the IL code buffer
// codeSize - number of bytes in the IL code buffer
// jumpTarget - [OUT] bit vector for flagging jump targets
//
// Notes:
-// If inlining or prejitting the root, this method also makes
+// If "makeInlineObservations" is true this method also makes
// various observations about the method that factor into inline
// decisions.
//
@@ -1080,6 +1083,7 @@ class FgStack
//
// Also sets m_addrExposed and lvHasILStoreOp, ilHasMultipleILStoreOp in lvaTable[].
//
+template <bool makeInlineObservations>
void Compiler::fgFindJumpTargets(const BYTE* codeAddr, IL_OFFSET codeSize, FixedBitVect* jumpTarget)
{
const BYTE* codeBegp = codeAddr;
@@ -1088,13 +1092,12 @@ void Compiler::fgFindJumpTargets(const BYTE* codeAddr, IL_OFFSET codeSize, Fixed
var_types varType = DUMMY_INIT(TYP_UNDEF); // TYP_ type
bool typeIsNormed = false;
FgStack pushedStack;
- const bool isForceInline = (info.compFlags & CORINFO_FLG_FORCEINLINE) != 0;
- const bool makeInlineObservations = (compInlineResult != nullptr);
- const bool isInlining = compIsForInlining();
- unsigned retBlocks = 0;
- int prefixFlags = 0;
- bool preciseScan = makeInlineObservations && compInlineResult->GetPolicy()->RequiresPreciseScan();
- const bool resolveTokens = preciseScan;
+ const bool isForceInline = (info.compFlags & CORINFO_FLG_FORCEINLINE) != 0;
+ const bool isInlining = compIsForInlining();
+ unsigned retBlocks = 0;
+ int prefixFlags = 0;
+ bool preciseScan = makeInlineObservations && compInlineResult->GetPolicy()->RequiresPreciseScan();
+ const bool resolveTokens = preciseScan;
// Track offsets where IL instructions begin in DEBUG builds. Used to
// validate debug info generated by the JIT.
@@ -3614,7 +3617,14 @@ void Compiler::fgFindBasicBlocks()
FixedBitVect* jumpTarget = FixedBitVect::bitVectInit(info.compILCodeSize + 1, this);
// Walk the instrs to find all jump targets
- fgFindJumpTargets(info.compCode, info.compILCodeSize, jumpTarget);
+ if (compInlineResult != nullptr)
+ {
+ fgFindJumpTargets<true>(info.compCode, info.compILCodeSize, jumpTarget);
+ }
+ else
+ {
+ fgFindJumpTargets<false>(info.compCode, info.compILCodeSize, jumpTarget);
+ }
if (compDonotInline())
{
return;