6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-12-14 11:32:34 +00:00
Code Issues Projects Releases Wiki Activity

Be more aggressive about tail-merging small blocks

Browse Source 
if those blocks consist entirely of common instructions;
merging will not add an extra branch in this case.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51006 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen 2008-05-12 22:53:12 +00:00
parent ae94dda61a
commit 30562b7d44
1 changed files with 12 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
lib/CodeGen/BranchFolding.cpp
View File

@ -495,7 +495,18 @@ unsigned BranchFolder::ComputeSameTails(unsigned CurHash,
CurMPIter->second,
I->second,
TrialBBI1, TrialBBI2);
if (CommonTailLen >= minCommonTailLength) {
// If we will have to split a block, there should be at least
// minCommonTailLength instructions in common; if not, at worst
// we will be replacing a fallthrough into the common tail with a
// branch, which at worst breaks even with falling through into
// the duplicated common tail, so 1 instruction in common is enough.
// We will always pick a block we do not have to split as the common
// tail if there is one.
// (Empty blocks will get forwarded and need not be considered.)
if (CommonTailLen >= minCommonTailLength ||
(CommonTailLen > 0 &&
(TrialBBI1==CurMPIter->second->begin() ||
TrialBBI2==I->second->begin()))) {
if (CommonTailLen > maxCommonTailLength) {
SameTails.clear();
maxCommonTailLength = CommonTailLen;