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Do not inline functions with (dynamic) alloca into

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functions that don't already have a (dynamic) alloca.
Dynamic allocas cause inefficient codegen and we shouldn't
propagate this (behavior follows gcc).  Two existing tests
assumed such inlining would be done; they are hacked by
adding an alloca in the caller, preserving the point of
the tests.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61946 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen 2009-01-08 21:45:23 +00:00
parent 86062afbc4
commit 4362387c74
5 changed files with 70 additions and 4 deletions
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7
include/llvm/Transforms/Utils/InlineCost.h
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@ -78,6 +78,9 @@ namespace llvm {
/// caller.
bool NeverInline;
/// usesDynamicAlloca - True if this function calls alloca (in the C sense).
bool usesDynamicAlloca;
/// NumInsts, NumBlocks - Keep track of how large each function is, which
/// is used to estimate the code size cost of inlining it.
unsigned NumInsts, NumBlocks;
@ -93,8 +96,8 @@ namespace llvm {
/// entry here.
std::vector<ArgInfo> ArgumentWeights;
FunctionInfo() : NeverInline(false), NumInsts(0), NumBlocks(0),
NumVectorInsts(0) {}
FunctionInfo() : NeverInline(false), usesDynamicAlloca(false), NumInsts(0),
NumBlocks(0), NumVectorInsts(0) {}
/// analyzeFunction - Fill in the current structure with information
/// gleaned from the specified function.

22
lib/Transforms/Utils/InlineCost.cpp
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@ -126,6 +126,11 @@ void InlineCostAnalyzer::FunctionInfo::analyzeFunction(Function *F) {
NumInsts += 5;
}
if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
if (!isa<ConstantInt>(AI->getArraySize()))
this->usesDynamicAlloca = true;
}
if (isa<ExtractElementInst>(II) || isa<VectorType>(II->getType()))
++NumVectorInsts;
@ -173,7 +178,7 @@ InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS,
SmallPtrSet<const Function *, 16> &NeverInline) {
Instruction *TheCall = CS.getInstruction();
Function *Callee = CS.getCalledFunction();
const Function *Caller = TheCall->getParent()->getParent();
Function *Caller = TheCall->getParent()->getParent();
// Don't inline a directly recursive call.
if (Caller == Callee ||
@ -219,11 +224,24 @@ InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS,
// If we haven't calculated this information yet, do so now.
if (CalleeFI.NumBlocks == 0)
CalleeFI.analyzeFunction(Callee);
// If we should never inline this, return a huge cost.
if (CalleeFI.NeverInline)
return InlineCost::getNever();
// Get infomation about the caller...
FunctionInfo &CallerFI = CachedFunctionInfo[Caller];
// If we haven't calculated this information yet, do so now.
if (CallerFI.NumBlocks == 0)
CallerFI.analyzeFunction(Caller);
// Don't inline a callee with dynamic alloca into a caller without them.
// Functions containing dynamic alloca's are inefficient in various ways;
// don't create more inefficiency.
if (CalleeFI.usesDynamicAlloca && !CallerFI.usesDynamicAlloca)
return InlineCost::getNever();
// FIXME: It would be nice to kill off CalleeFI.NeverInline. Then we
// could move this up and avoid computing the FunctionInfo for
// things we are going to just return always inline for. This

36
test/Transforms/Inline/2009-01-08-NoInlineDynamicAlloca.ll Normal file
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@ -0,0 +1,36 @@
; RUN: llvm-as < %s | opt -inline | llvm-dis | grep call
; Do not inline calls to variable-sized alloca.
@q = common global i8* null ; <i8**> [#uses=1]
define i8* @a(i32 %i) nounwind {
entry:
%i_addr = alloca i32 ; <i32*> [#uses=2]
%retval = alloca i8* ; <i8**> [#uses=1]
%p = alloca i8* ; <i8**> [#uses=2]
%"alloca point" = bitcast i32 0 to i32 ; <i32> [#uses=0]
store i32 %i, i32* %i_addr
%0 = load i32* %i_addr, align 4 ; <i32> [#uses=1]
%1 = alloca i8, i32 %0 ; <i8*> [#uses=1]
store i8* %1, i8** %p, align 4
%2 = load i8** %p, align 4 ; <i8*> [#uses=1]
store i8* %2, i8** @q, align 4
br label %return
return: ; preds = %entry
%retval1 = load i8** %retval ; <i8*> [#uses=1]
ret i8* %retval1
}
define void @b(i32 %i) nounwind {
entry:
%i_addr = alloca i32 ; <i32*> [#uses=2]
%"alloca point" = bitcast i32 0 to i32 ; <i32> [#uses=0]
store i32 %i, i32* %i_addr
%0 = load i32* %i_addr, align 4 ; <i32> [#uses=1]
%1 = call i8* @a(i32 %0) nounwind ; <i8*> [#uses=0]
br label %return
return: ; preds = %entry
ret void
}

4
test/Transforms/Inline/dynamic_alloca_test.ll
View File

@ -1,5 +1,7 @@
; Test that functions with dynamic allocas get inlined in a case where
; naively inlining it would result in a miscompilation.
; Functions with dynamic allocas can only be inlined into functions that
; already have dynamic allocas.
; RUN: llvm-as < %s | opt -inline | llvm-dis | \
; RUN: grep llvm.stacksave
@ -16,6 +18,8 @@ define internal void @callee(i32 %N) {
define void @foo(i32 %N) {
; <label>:0
%P = alloca i32, i32 %N ; <i32*> [#uses=1]
call void @ext( i32* %P )
br label %Loop
Loop: ; preds = %Loop, %0

5
test/Transforms/PruneEH/2008-09-05-CGUpdate.ll
View File

@ -636,6 +636,9 @@ lpad: ; preds = %entry, %invcont
define internal fastcc i32 @ce3806g__fxio__put__4.1215(i8* %to.0, %struct.string___XUB* %to.1, i8 signext %item) {
entry:
%P0 = load i32 * @__gnat_all_others_value, align 4 ; <i32*> [#uses=1]
%P = alloca i32, i32 %P0 ; <i32*> [#uses=1]
call void @ext( i32* %P )
%to_addr = alloca %struct.system__file_control_block__pstring ; <%struct.system__file_control_block__pstring*> [#uses=4]
%FRAME.358 = alloca %struct.FRAME.ce3806g__fxio__put__4 ; <%struct.FRAME.ce3806g__fxio__put__4*> [#uses=65]
%0 = getelementptr %struct.system__file_control_block__pstring* %to_addr, i32 0, i32 0 ; <i8**> [#uses=1]
@ -1435,6 +1438,8 @@ declare %struct.ada__text_io__text_afcb* @ada__text_io__standard_output()
declare void @report__failed(i8*, %struct.string___XUB*)
declare void @ext(i32*)
declare %struct.ada__text_io__text_afcb* @ada__text_io__delete(%struct.ada__text_io__text_afcb*)
declare void @report__result()