Inlining and unrolling heuristics should be aware of free truncs.
We want heuristics to be based on accurate data, but more importantly
we don't want llvm to behave randomly. A benign trunc inserted by an
upstream pass should not cause a wild swings in optimization
level. See PR11034. It's a general problem with threshold-based
heuristics, but we can make it less bad.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140919 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/InlineCost.cpp b/lib/Analysis/InlineCost.cpp
index 7ec7ae5..e12e322 100644
--- a/lib/Analysis/InlineCost.cpp
+++ b/lib/Analysis/InlineCost.cpp
@@ -15,6 +15,7 @@
#include "llvm/Support/CallSite.h"
#include "llvm/CallingConv.h"
#include "llvm/IntrinsicInst.h"
+#include "llvm/Target/TargetData.h"
#include "llvm/ADT/SmallPtrSet.h"
using namespace llvm;
@@ -52,7 +53,8 @@
/// analyzeBasicBlock - Fill in the current structure with information gleaned
/// from the specified block.
-void CodeMetrics::analyzeBasicBlock(const BasicBlock *BB) {
+void CodeMetrics::analyzeBasicBlock(const BasicBlock *BB,
+ const TargetData *TD) {
++NumBlocks;
unsigned NumInstsBeforeThisBB = NumInsts;
for (BasicBlock::const_iterator II = BB->begin(), E = BB->end();
@@ -105,6 +107,11 @@
if (CI->isLosslessCast() || isa<IntToPtrInst>(CI) ||
isa<PtrToIntInst>(CI))
continue;
+ // trunc to a native type is free (assuming the target has compare and
+ // shift-right of the same width).
+ if (isa<TruncInst>(CI) && TD &&
+ TD->isLegalInteger(TD->getTypeSizeInBits(CI->getType())))
+ continue;
// Result of a cmp instruction is often extended (to be used by other
// cmp instructions, logical or return instructions). These are usually
// nop on most sane targets.
@@ -217,7 +224,7 @@
/// analyzeFunction - Fill in the current structure with information gleaned
/// from the specified function.
-void CodeMetrics::analyzeFunction(Function *F) {
+void CodeMetrics::analyzeFunction(Function *F, const TargetData *TD) {
// If this function contains a call to setjmp or _setjmp, never inline
// it. This is a hack because we depend on the user marking their local
// variables as volatile if they are live across a setjmp call, and they
@@ -227,13 +234,14 @@
// Look at the size of the callee.
for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
- analyzeBasicBlock(&*BB);
+ analyzeBasicBlock(&*BB, TD);
}
/// analyzeFunction - Fill in the current structure with information gleaned
/// from the specified function.
-void InlineCostAnalyzer::FunctionInfo::analyzeFunction(Function *F) {
- Metrics.analyzeFunction(F);
+void InlineCostAnalyzer::FunctionInfo::analyzeFunction(Function *F,
+ const TargetData *TD) {
+ Metrics.analyzeFunction(F, TD);
// A function with exactly one return has it removed during the inlining
// process (see InlineFunction), so don't count it.
@@ -275,7 +283,7 @@
// If we haven't calculated this information yet, do so now.
if (CalleeFI->Metrics.NumBlocks == 0)
- CalleeFI->analyzeFunction(Callee);
+ CalleeFI->analyzeFunction(Callee, TD);
unsigned ArgNo = 0;
unsigned i = 0;
@@ -365,7 +373,7 @@
// If we haven't calculated this information yet, do so now.
if (CalleeFI->Metrics.NumBlocks == 0)
- CalleeFI->analyzeFunction(Callee);
+ CalleeFI->analyzeFunction(Callee, TD);
// InlineCost - This value measures how good of an inline candidate this call
// site is to inline. A lower inline cost make is more likely for the call to
@@ -418,7 +426,7 @@
// If we haven't calculated this information yet, do so now.
if (CalleeFI->Metrics.NumBlocks == 0)
- CalleeFI->analyzeFunction(Callee);
+ CalleeFI->analyzeFunction(Callee, TD);
bool isDirectCall = CS.getCalledFunction() == Callee;
Instruction *TheCall = CS.getInstruction();
@@ -486,7 +494,7 @@
// If we haven't calculated this information yet, do so now.
if (CalleeFI->Metrics.NumBlocks == 0)
- CalleeFI->analyzeFunction(Callee);
+ CalleeFI->analyzeFunction(Callee, TD);
// If we should never inline this, return a huge cost.
if (CalleeFI->NeverInline())
@@ -505,7 +513,7 @@
// If we haven't calculated this information yet, do so now.
if (CallerFI.Metrics.NumBlocks == 0) {
- CallerFI.analyzeFunction(Caller);
+ CallerFI.analyzeFunction(Caller, TD);
// Recompute the CalleeFI pointer, getting Caller could have invalidated
// it.
@@ -544,7 +552,7 @@
// If we haven't calculated this information yet, do so now.
if (CalleeFI->Metrics.NumBlocks == 0)
- CalleeFI->analyzeFunction(Callee);
+ CalleeFI->analyzeFunction(Callee, TD);
int Cost = 0;
@@ -570,7 +578,7 @@
// If we haven't calculated this information yet, do so now.
if (CalleeFI.Metrics.NumBlocks == 0)
- CalleeFI.analyzeFunction(Callee);
+ CalleeFI.analyzeFunction(Callee, TD);
float Factor = 1.0f;
// Single BB functions are often written to be inlined.