Commit Graph

3 Commits

Author SHA1 Message Date
Dan Gohman 1ccecdb2fd Reapply r155682, making constant folding more consistent, with a fix to work
properly with how the code handles all-undef PHI nodes.

llvm-svn: 155721
2012-04-27 17:50:22 +00:00
NAKAMURA Takumi 6008dfdb70 Revert r155682, "Use ConstantExpr::getExtractElement when constant-folding vectors"
It broke stage2 build. stage1/clang sometimes crashed.

llvm-svn: 155699
2012-04-27 07:59:20 +00:00
Dan Gohman 90f3798f26 Use ConstantExpr::getExtractElement when constant-folding vectors
instead of getAggregateElement. This has the advantage of being
more consistent and allowing higher-level constant folding to
procede even if an inner extract element cannot be folded.

Make ConstantFoldInstruction call ConstantFoldConstantExpression
on the instruction's operands, making it more consistent with 
ConstantFoldConstantExpression itself. This makes sure that
ConstantExprs get TargetData-aware folding before being handed
off as operands for further folding.

This causes more expressions to be folded, but due to a known
shortcoming in constant folding, this currently has the side effect
of stripping a few more nuw and inbounds flags in the non-targetdata
side of constant-fold-gep.ll. This is mostly harmless.

This fixes rdar://11324230.

llvm-svn: 155682
2012-04-27 00:54:36 +00:00