Author: baldrick
Date: Mon Dec 10 13:09:40 2007
New Revision: 44802
URL: http://llvm.org/viewvc/llvm-project?rev=44802&view=rev
Log:
Make PruneEH update the nounwind/noreturn attributes
on functions as it calculates them.
Added:
llvm/trunk/test/Transforms/PruneEH/simpletest.ll
Removed:
llvm/trunk/test/Transforms/PruneEH/simpletest.llx
Modified:
llvm/trunk/include/llvm/Function.h
llvm/trunk/include/llvm/Instructions.h
llvm/trunk/lib/Transforms/IPO/PruneEH.cpp
llvm/trunk/lib/Transforms/Scalar/SimplifyCFG.cpp
llvm/trunk/test/Transforms/PruneEH/simplenoreturntest.ll
Modified: llvm/trunk/include/llvm/Function.h
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Function.h?rev=44802&r1=44801&r2=44802&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Function.h (original)
+++ llvm/trunk/include/llvm/Function.h Mon Dec 10 13:09:40 2007
@@ -165,6 +165,16 @@
return ParamAttrs && ParamAttrs->paramHasAttr(i, attr);
}
+ /// @brief Determine if the function cannot return.
+ bool isNoReturn() const {
+ return paramHasAttr(0, ParamAttr::NoReturn);
+ }
+
+ /// @brief Determine if the function cannot unwind.
+ bool isNoUnwind() const {
+ return paramHasAttr(0, ParamAttr::NoUnwind);
+ }
+
/// @brief Determine if the function does not access memory.
bool doesNotAccessMemory() const {
return paramHasAttr(0, ParamAttr::ReadNone);
Modified: llvm/trunk/include/llvm/Instructions.h
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Instructions.h?rev=44802&r1=44801&r2=44802&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Instructions.h (original)
+++ llvm/trunk/include/llvm/Instructions.h Mon Dec 10 13:09:40 2007
@@ -937,6 +937,11 @@
return doesNotAccessMemory() || paramHasAttr(0, ParamAttr::ReadOnly);
}
+ /// @brief Determine if the call cannot return.
+ bool isNoReturn() const {
+ return paramHasAttr(0, ParamAttr::NoReturn);
+ }
+
/// @brief Determine if the call cannot unwind.
bool isNoUnwind() const {
return paramHasAttr(0, ParamAttr::NoUnwind);
@@ -1736,6 +1741,11 @@
return doesNotAccessMemory() || paramHasAttr(0, ParamAttr::ReadOnly);
}
+ /// @brief Determine if the call cannot return.
+ bool isNoReturn() const {
+ return paramHasAttr(0, ParamAttr::NoReturn);
+ }
+
/// @brief Determine if the call cannot unwind.
bool isNoUnwind() const {
return paramHasAttr(0, ParamAttr::NoUnwind);
Modified: llvm/trunk/lib/Transforms/IPO/PruneEH.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PruneEH.cpp?rev=44802&r1=44801&r2=44802&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/PruneEH.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/PruneEH.cpp Mon Dec 10 13:09:40 2007
@@ -9,8 +9,8 @@
//
// This file implements a simple interprocedural pass which walks the
// call-graph, turning invoke instructions into calls, iff the callee cannot
-// throw an exception. It implements this as a bottom-up traversal of the
-// call-graph.
+// throw an exception, and marking functions 'nounwind' if they cannot throw.
+// It implements this as a bottom-up traversal of the call-graph.
//
//===----------------------------------------------------------------------===//
@@ -19,7 +19,6 @@
#include "llvm/CallGraphSCCPass.h"
#include "llvm/Constants.h"
#include "llvm/Function.h"
-#include "llvm/Intrinsics.h"
#include "llvm/Instructions.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/ADT/SmallVector.h"
@@ -38,14 +37,6 @@
static char ID; // Pass identification, replacement for typeid
PruneEH() : CallGraphSCCPass((intptr_t)&ID) {}
- /// DoesNotUnwind - This set contains all of the functions which we have
- /// determined cannot unwind.
- std::set<CallGraphNode*> DoesNotUnwind;
-
- /// DoesNotReturn - This set contains all of the functions which we have
- /// determined cannot return normally (but might unwind).
- std::set<CallGraphNode*> DoesNotReturn;
-
// runOnSCC - Analyze the SCC, performing the transformation if possible.
bool runOnSCC(const std::vector<CallGraphNode *> &SCC);
@@ -79,33 +70,41 @@
for (unsigned i = 0, e = SCC.size();
(!SCCMightUnwind || !SCCMightReturn) && i != e; ++i) {
Function *F = SCC[i]->getFunction();
- if (F == 0 || (F->isDeclaration() && !F->getIntrinsicID())) {
+ if (F == 0) {
SCCMightUnwind = true;
SCCMightReturn = true;
+ } else if (F->isDeclaration()) {
+ SCCMightUnwind |= !F->isNoUnwind();
+ SCCMightReturn |= !F->isNoReturn();
} else {
- if (F->isDeclaration())
- SCCMightReturn = true;
+ bool CheckUnwind = !SCCMightUnwind && !F->isNoUnwind();
+ bool CheckReturn = !SCCMightReturn && !F->isNoReturn();
+
+ if (!CheckUnwind && !CheckReturn)
+ continue;
// Check to see if this function performs an unwind or calls an
// unwinding function.
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
- if (isa<UnwindInst>(BB->getTerminator())) { // Uses unwind!
+ if (CheckUnwind && isa<UnwindInst>(BB->getTerminator())) {
+ // Uses unwind!
SCCMightUnwind = true;
- } else if (isa<ReturnInst>(BB->getTerminator())) {
+ } else if (CheckReturn && isa<ReturnInst>(BB->getTerminator())) {
SCCMightReturn = true;
}
// Invoke instructions don't allow unwinding to continue, so we are
// only interested in call instructions.
- if (!SCCMightUnwind)
+ if (CheckUnwind && !SCCMightUnwind)
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;
++I)
if (CallInst *CI = dyn_cast<CallInst>(I)) {
- if (Function *Callee = CI->getCalledFunction()) {
+ if (CI->isNoUnwind()) {
+ // This call cannot throw.
+ } else if (Function *Callee = CI->getCalledFunction()) {
CallGraphNode *CalleeNode = CG[Callee];
- // If the callee is outside our current SCC, or if it is not
- // known to throw, then we might throw also.
- if (std::find(SCC.begin(), SCC.end(), CalleeNode) ==
SCC.end()&&
- !DoesNotUnwind.count(CalleeNode)) {
+ // If the callee is outside our current SCC then we may
+ // throw because it might.
+ if (std::find(SCC.begin(), SCC.end(), CalleeNode) ==
SCC.end()){
SCCMightUnwind = true;
break;
}
@@ -121,12 +120,21 @@
}
// If the SCC doesn't unwind or doesn't throw, note this fact.
- if (!SCCMightUnwind)
- for (unsigned i = 0, e = SCC.size(); i != e; ++i)
- DoesNotUnwind.insert(SCC[i]);
- if (!SCCMightReturn)
- for (unsigned i = 0, e = SCC.size(); i != e; ++i)
- DoesNotReturn.insert(SCC[i]);
+ if (!SCCMightUnwind || !SCCMightReturn)
+ for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
+ const ParamAttrsList *PAL = SCC[i]->getFunction()->getParamAttrs();
+ uint16_t RAttributes = PAL ? PAL->getParamAttrs(0) : 0;
+
+ if (!SCCMightUnwind)
+ RAttributes |= ParamAttr::NoUnwind;
+ if (!SCCMightReturn)
+ RAttributes |= ParamAttr::NoReturn;
+
+ ParamAttrsVector modVec;
+ modVec.push_back(ParamAttrsWithIndex::get(0, RAttributes));
+ PAL = ParamAttrsList::getModified(PAL, modVec);
+ SCC[i]->getFunction()->setParamAttrs(PAL);
+ }
for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
// Convert any invoke instructions to non-throwing functions in this node
@@ -144,61 +152,58 @@
// function if we have invokes to non-unwinding functions or code after calls
to
// no-return functions.
bool PruneEH::SimplifyFunction(Function *F) {
- CallGraph &CG = getAnalysis<CallGraph>();
bool MadeChange = false;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator()))
- if (Function *F = II->getCalledFunction())
- if (DoesNotUnwind.count(CG[F])) {
- SmallVector<Value*, 8> Args(II->op_begin()+3, II->op_end());
- // Insert a call instruction before the invoke.
- CallInst *Call = new CallInst(II->getCalledValue(),
- Args.begin(), Args.end(), "", II);
- Call->takeName(II);
- Call->setCallingConv(II->getCallingConv());
- Call->setParamAttrs(II->getParamAttrs());
-
- // Anything that used the value produced by the invoke instruction
- // now uses the value produced by the call instruction.
- II->replaceAllUsesWith(Call);
- BasicBlock *UnwindBlock = II->getUnwindDest();
- UnwindBlock->removePredecessor(II->getParent());
-
- // Insert a branch to the normal destination right before the
- // invoke.
- new BranchInst(II->getNormalDest(), II);
+ if (II->isNoUnwind()) {
+ SmallVector<Value*, 8> Args(II->op_begin()+3, II->op_end());
+ // Insert a call instruction before the invoke.
+ CallInst *Call = new CallInst(II->getCalledValue(),
+ Args.begin(), Args.end(), "", II);
+ Call->takeName(II);
+ Call->setCallingConv(II->getCallingConv());
+ Call->setParamAttrs(II->getParamAttrs());
+
+ // Anything that used the value produced by the invoke instruction
+ // now uses the value produced by the call instruction.
+ II->replaceAllUsesWith(Call);
+ BasicBlock *UnwindBlock = II->getUnwindDest();
+ UnwindBlock->removePredecessor(II->getParent());
+
+ // Insert a branch to the normal destination right before the
+ // invoke.
+ new BranchInst(II->getNormalDest(), II);
+
+ // Finally, delete the invoke instruction!
+ BB->getInstList().pop_back();
+
+ // If the unwind block is now dead, nuke it.
+ if (pred_begin(UnwindBlock) == pred_end(UnwindBlock))
+ DeleteBasicBlock(UnwindBlock); // Delete the new BB.
- // Finally, delete the invoke instruction!
- BB->getInstList().pop_back();
+ ++NumRemoved;
+ MadeChange = true;
+ }
- // If the unwind block is now dead, nuke it.
- if (pred_begin(UnwindBlock) == pred_end(UnwindBlock))
- DeleteBasicBlock(UnwindBlock); // Delete the new BB.
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; )
+ if (CallInst *CI = dyn_cast<CallInst>(I++))
+ if (CI->isNoReturn() && !isa<UnreachableInst>(I)) {
+ // This call calls a function that cannot return. Insert an
+ // unreachable instruction after it and simplify the code. Do this
+ // by splitting the BB, adding the unreachable, then deleting the
+ // new BB.
+ BasicBlock *New = BB->splitBasicBlock(I);
+
+ // Remove the uncond branch and add an unreachable.
+ BB->getInstList().pop_back();
+ new UnreachableInst(BB);
- ++NumRemoved;
+ DeleteBasicBlock(New); // Delete the new BB.
MadeChange = true;
+ ++NumUnreach;
+ break;
}
- for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; )
- if (CallInst *CI = dyn_cast<CallInst>(I++))
- if (Function *Callee = CI->getCalledFunction())
- if (DoesNotReturn.count(CG[Callee]) && !isa<UnreachableInst>(I)) {
- // This call calls a function that cannot return. Insert an
- // unreachable instruction after it and simplify the code. Do this
- // by splitting the BB, adding the unreachable, then deleting the
- // new BB.
- BasicBlock *New = BB->splitBasicBlock(I);
-
- // Remove the uncond branch and add an unreachable.
- BB->getInstList().pop_back();
- new UnreachableInst(BB);
-
- DeleteBasicBlock(New); // Delete the new BB.
- MadeChange = true;
- ++NumUnreach;
- break;
- }
-
}
return MadeChange;
}
Modified: llvm/trunk/lib/Transforms/Scalar/SimplifyCFG.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SimplifyCFG.cpp?rev=44802&r1=44801&r2=44802&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SimplifyCFG.cpp Mon Dec 10 13:09:40 2007
@@ -111,7 +111,7 @@
// canonicalizes unreachable insts into stores to null or undef.
for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI !=
E;++BBI){
if (CallInst *CI = dyn_cast<CallInst>(BBI)) {
- if (CI->paramHasAttr(0, ParamAttr::NoReturn)) {
+ if (CI->isNoReturn()) {
// If we found a call to a no-return function, insert an unreachable
// instruction after it. Make sure there isn't *already* one there
// though.
Modified: llvm/trunk/test/Transforms/PruneEH/simplenoreturntest.ll
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/PruneEH/simplenoreturntest.ll?rev=44802&r1=44801&r2=44802&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/PruneEH/simplenoreturntest.ll (original)
+++ llvm/trunk/test/Transforms/PruneEH/simplenoreturntest.ll Mon Dec 10
13:09:40 2007
@@ -1,17 +1,13 @@
-; RUN: llvm-upgrade < %s | llvm-as | opt -prune-eh | llvm-dis | \
-; RUN: not grep {ret i32}
+; RUN: llvm-as < %s | opt -prune-eh | llvm-dis | not grep {ret i32}
-void %noreturn() {
- unwind
-}
+declare void @noreturn() noreturn;
-int %caller() {
- ; noreturn never returns, so the ret is unreachable.
- call void %noreturn()
- ret int 17
+define i32 @caller() {
+ call void @noreturn( )
+ ret i32 17
}
-int %caller2() {
- %T = call int %caller()
- ret int %T ;; this is also unreachable!
+define i32 @caller2() {
+ %T = call i32 @caller( ) ; <i32> [#uses=1]
+ ret i32 %T
}
Added: llvm/trunk/test/Transforms/PruneEH/simpletest.ll
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/PruneEH/simpletest.ll?rev=44802&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/PruneEH/simpletest.ll (added)
+++ llvm/trunk/test/Transforms/PruneEH/simpletest.ll Mon Dec 10 13:09:40 2007
@@ -0,0 +1,19 @@
+; RUN: llvm-as < %s | opt -prune-eh | llvm-dis | not grep invoke
+
+declare void @nounwind() nounwind
+
+define internal void @foo() {
+ call void @nounwind()
+ ret void
+}
+
+define i32 @caller() {
+ invoke void @foo( )
+ to label %Normal unwind label %Except
+
+Normal: ; preds = %0
+ ret i32 0
+
+Except: ; preds = %0
+ ret i32 1
+}
Removed: llvm/trunk/test/Transforms/PruneEH/simpletest.llx
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/PruneEH/simpletest.llx?rev=44801&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/PruneEH/simpletest.llx (original)
+++ llvm/trunk/test/Transforms/PruneEH/simpletest.llx (removed)
@@ -1,15 +0,0 @@
-; RUN: llvm-upgrade < %s | llvm-as | opt -prune-eh | llvm-dis | not grep invoke
-
-implementation
-
-internal void %foo() {
- ret void ; does not throw
-}
-
-int %caller() {
- invoke void %foo() to label %Normal except label %Except
-Normal:
- ret int 0
-Except:
- ret int 1
-}
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