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ISO 9899 7.13.2.1 (3) says that "[...] the values of objects of automatic 

storage duration that are local to the function containing the invocation of the
[...] setjmp macro that do not have volatile-qualified type and have been
changed between the setjmp invocation and longjmp call are indeterminate."

As such, we have to mark all variables in a function that uses 'invoke' as
volatile.

This fixes PR77

llvm-svn: 10035
This commit is contained in:
Chris Lattner 2003-11-16 22:06:14 +00:00
parent eec1307f43
commit 9005b8000c
1 changed files with 39 additions and 4 deletions
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41
llvm/lib/CWriter/Writer.cpp
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@ -564,7 +564,7 @@ bool CWriter::nameAllUsedStructureTypes(Module &M) {
// generateCompilerSpecificCode - This is where we add conditional compilation
// directives to cater to specific compilers as need be.
//
void generateCompilerSpecificCode(std::ostream& Out) {
static void generateCompilerSpecificCode(std::ostream& Out) {
// Alloca is hard to get, and we don't want to include stdlib.h here...
Out << "/* get a declaration for alloca */\n"
<< "#ifdef sun\n"
@ -583,6 +583,29 @@ void generateCompilerSpecificCode(std::ostream& Out) {
<< "#endif\n";
}
// generateProcessorSpecificCode - This is where we add conditional compilation
// directives to cater to specific processors as need be.
//
static void generateProcessorSpecificCode(std::ostream& Out) {
// According to ANSI C, longjmp'ing to a setjmp could invalidate any
// non-volatile variable in the scope of the setjmp. For now, we are not
// doing analysis to determine which variables need to be marked volatile, so
// we just mark them all.
//
// HOWEVER, many targets implement setjmp by saving and restoring the register
// file, so they DON'T need variables to be marked volatile, and this is a
// HUGE pessimization for them. For this reason, on known-good processors, we
// do not emit volatile qualifiers.
Out << "#if defined(__386__) || defined(__i386__) || \\\n"
<< " defined(i386) || defined(WIN32)\n"
<< "/* setjmp does not require variables to be marked volatile */"
<< "#define VOLATILE_FOR_SETJMP\n"
<< "#else\n"
<< "#define VOLATILE_FOR_SETJMP volatile\n"
<< "#endif\n\n";
}
void CWriter::printModule(Module *M) {
// Calculate which global values have names that will collide when we throw
// away type information.
@ -605,9 +628,10 @@ void CWriter::printModule(Module *M) {
// get declaration for alloca
Out << "/* Provide Declarations */\n";
Out << "#include <stdarg.h>\n";
Out << "#include <setjmp.h>\n";
Out << "#include <stdarg.h>\n"; // Varargs support
Out << "#include <setjmp.h>\n"; // Unwind support
generateCompilerSpecificCode(Out);
generateProcessorSpecificCode(Out);
// Provide a definition for `bool' if not compiling with a C++ compiler.
Out << "\n"
@ -924,19 +948,30 @@ void CWriter::printFunction(Function *F) {
printFunctionSignature(F, false);
Out << " {\n";
// Determine whether or not the function contains any invoke instructions.
bool HasInvoke = false;
for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I)
if (isa<InvokeInst>(I->getTerminator())) {
HasInvoke = true;
break;
}
// print local variable information for the function
for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
if (const AllocaInst *AI = isDirectAlloca(*I)) {
Out << " ";
if (HasInvoke) Out << "VOLATILE_FOR_SETJMP ";
printType(Out, AI->getAllocatedType(), Mang->getValueName(AI));
Out << "; /* Address exposed local */\n";
} else if ((*I)->getType() != Type::VoidTy && !isInlinableInst(**I)) {
Out << " ";
if (HasInvoke) Out << "VOLATILE_FOR_SETJMP ";
printType(Out, (*I)->getType(), Mang->getValueName(*I));
Out << ";\n";
if (isa<PHINode>(*I)) { // Print out PHI node temporaries as well...
Out << " ";
if (HasInvoke) Out << "VOLATILE_FOR_SETJMP ";
printType(Out, (*I)->getType(),
Mang->getValueName(*I)+"__PHI_TEMPORARY");
Out << ";\n";