6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-01-19 20:34:38 +00:00
Code Issues Projects Releases Wiki Activity

Eliminate more token factors by taking advantage of transitivity:

Browse Source 
if TF depends on A and B, and A depends on B, TF just needs to depend on
A.  With Jim's alias-analysis stuff enabled, this compiles the testcase in
PR892 into:

__Z4test3Val:
        subl $44, %esp
        call L__Z3foov$stub
        movl %edx, 28(%esp)
        movl %eax, 32(%esp)
        movl %eax, 24(%esp)
        movl %edx, 36(%esp)
        movl 52(%esp), %ecx
        movl %ecx, 4(%esp)
        movl %eax, 8(%esp)
        movl %edx, 12(%esp)
        movl 48(%esp), %eax
        movl %eax, (%esp)
        call L__Z3bar3ValS_$stub
        addl $44, %esp
        ret

instead of:

__Z4test3Val:
        subl $44, %esp
        call L__Z3foov$stub
        movl %eax, 24(%esp)
        movl %edx, 28(%esp)
        movl 24(%esp), %eax
        movl %eax, 32(%esp)
        movl 28(%esp), %eax
        movl %eax, 36(%esp)
        movl 32(%esp), %eax
        movl 36(%esp), %ecx
        movl 52(%esp), %edx
        movl %edx, 4(%esp)
        movl %eax, 8(%esp)
        movl %ecx, 12(%esp)
        movl 48(%esp), %eax
        movl %eax, (%esp)
        call L__Z3bar3ValS_$stub
        addl $44, %esp
        ret


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30821 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-10-08 22:57:01 +00:00
parent 53b06db6c7
commit 6270f686b3
1 changed files with 25 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -518,7 +518,32 @@ SDOperand DAGCombiner::visit(SDNode *N) {
return SDOperand(); return SDOperand();
} }
/// getInputChainForNode - Given a node, return its input chain if it has one,
/// otherwise return a null sd operand.
static SDOperand getInputChainForNode(SDNode *N) {
if (unsigned NumOps = N->getNumOperands()) {
if (N->getOperand(0).getValueType() == MVT::Other)
return N->getOperand(0);
else if (N->getOperand(NumOps-1).getValueType() == MVT::Other)
return N->getOperand(NumOps-1);
for (unsigned i = 1; i < NumOps-1; ++i)
if (N->getOperand(i).getValueType() == MVT::Other)
return N->getOperand(i);
}
return SDOperand(0, 0);
}
SDOperand DAGCombiner::visitTokenFactor(SDNode *N) { SDOperand DAGCombiner::visitTokenFactor(SDNode *N) {
// If N has two operands, where one has an input chain equal to the other,
// the 'other' chain is redundant.
if (N->getNumOperands() == 2) {
if (getInputChainForNode(N->getOperand(0).Val) == N->getOperand(1))
return N->getOperand(0);
if (getInputChainForNode(N->getOperand(1).Val) == N->getOperand(0))
return N->getOperand(1);
}
SmallVector<SDNode *, 8> TFs; // List of token factors to visit. SmallVector<SDNode *, 8> TFs; // List of token factors to visit.
SmallVector<SDOperand, 8> Ops; // Ops for replacing token factor. SmallVector<SDOperand, 8> Ops; // Ops for replacing token factor.
bool Changed = false; // If we should replace this token factor. bool Changed = false; // If we should replace this token factor.