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Adjust stack alignment for local variables to work more like arguments.

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This makes it easier to generate frame-pointer-relative addresses for ARM.

Prior to this we had stored char sized local variables in the highest
address of the 4-byte stack allocation. Now we store "char"s in the
lowest address of the 4-byte stack allocation, just like chars are
passed as arguments.

We now store global chars on byte boundaries.
This commit is contained in:
Jack Palevich 2009-07-23 18:56:20 -07:00
parent 894c5cd214
commit 7fcdf1c5f8
1 changed files with 43 additions and 7 deletions
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50
libacc/acc.cpp
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@ -481,14 +481,27 @@ class Compiler : public ErrorSink {
virtual size_t sizeOf(Type* type) = 0;
/**
* Stack argument size of this data type.
* Stack alignment of this type of data
*/
virtual size_t stackAlignmentOf(Type* pType) = 0;
/**
* Argument stack argument size of this data type.
*/
virtual size_t stackSizeOf(Type* pType) = 0;
virtual Type* getR0Type() {
Type* getR0Type() {
return mExpressionStack.back().pType;
}
ExpressionType getR0ExpressionType() {
return mExpressionStack.back().et;
}
void setR0ExpressionType(ExpressionType et) {
mExpressionStack.back().et = et;
}
protected:
/*
* Output a byte. Handles all values, 0..ff.
@ -1450,6 +1463,8 @@ class Compiler : public ErrorSink {
*/
virtual size_t alignmentOf(Type* pType){
switch(pType->tag) {
case TY_CHAR:
return 1;
case TY_DOUBLE:
return 8;
default:
@ -1477,6 +1492,15 @@ class Compiler : public ErrorSink {
}
}
virtual size_t stackAlignmentOf(Type* pType) {
switch(pType->tag) {
case TY_DOUBLE:
return 8;
default:
return 4;
}
}
virtual size_t stackSizeOf(Type* pType) {
switch(pType->tag) {
case TY_DOUBLE:
@ -2381,7 +2405,12 @@ class Compiler : public ErrorSink {
* Alignment (in bytes) for this type of data
*/
virtual size_t alignmentOf(Type* pType){
return 4;
switch (pType->tag) {
case TY_CHAR:
return 1;
default:
return 4;
}
}
/**
@ -2404,6 +2433,10 @@ class Compiler : public ErrorSink {
}
}
virtual size_t stackAlignmentOf(Type* pType){
return 4;
}
virtual size_t stackSizeOf(Type* pType) {
switch(pType->tag) {
case TY_DOUBLE:
@ -4538,9 +4571,12 @@ class Compiler : public ErrorSink {
}
int variableAddress = 0;
addLocalSymbol(pDecl);
size_t alignment = pGen->alignmentOf(pDecl);
loc = (loc + alignment - 1) & ~ (alignment-1);
loc = loc + pGen->sizeOf(pDecl);
size_t alignment = pGen->stackAlignmentOf(pDecl);
size_t alignmentMask = ~ (alignment - 1);
size_t sizeOf = pGen->sizeOf(pDecl);
loc = (loc + alignment - 1) & alignmentMask;
size_t alignedSize = (sizeOf + alignment - 1) & alignmentMask;
loc = loc + alignedSize;
variableAddress = -loc;
VI(pDecl->id)->pAddress = (void*) variableAddress;
if (accept('=')) {
@ -4674,7 +4710,7 @@ class Compiler : public ErrorSink {
Type* pArg = pP->pHead;
addLocalSymbol(pArg);
/* read param name and compute offset */
size_t alignment = pGen->alignmentOf(pArg);
size_t alignment = pGen->stackAlignmentOf(pArg);
a = (a + alignment - 1) & ~ (alignment-1);
VI(pArg->id)->pAddress = (void*) a;
a = a + pGen->stackSizeOf(pArg);