6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-05-24 02:38:42 +00:00
Code Issues Projects Releases Wiki Activity

Do not try to optimize PHI nodes with incredibly high degree. This reduces SCCP

Browse Source 
time from 615s to 1.49s on a large testcase that has a gigantic switch statement
that all of the blocks in the function go to (an intepreter).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12442 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-03-16 19:49:59 +00:00
parent 4bebf08d15
commit a2f652d420
1 changed files with 7 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
lib/Transforms/Scalar/SCCP.cpp
View File

@ -500,6 +500,13 @@ void SCCP::visitPHINode(PHINode &PN) {
return; // Quick exit return; // Quick exit
} }
// Super-extra-high-degree PHI nodes are unlikely to ever be marked constant,
// and slow us down a lot. Just mark them overdefined.
if (PN.getNumIncomingValues() > 64) {
markOverdefined(PNIV, &PN);
return;
}
// Look at all of the executable operands of the PHI node. If any of them // Look at all of the executable operands of the PHI node. If any of them
// are overdefined, the PHI becomes overdefined as well. If they are all // are overdefined, the PHI becomes overdefined as well. If they are all
// constant, and they agree with each other, the PHI becomes the identical // constant, and they agree with each other, the PHI becomes the identical