diff options
Diffstat (limited to 'llvm/lib/Transforms')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstructionCombining.cpp | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index b332e75c7fe..538d37192bd 100644 --- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -144,12 +144,20 @@ Value *InstCombiner::EmitGEPOffset(User *GEP) { /// We don't want to convert from a legal to an illegal type or from a smaller /// to a larger illegal type. A width of '1' is always treated as a legal type /// because i1 is a fundamental type in IR, and there are many specialized -/// optimizations for i1 types. +/// optimizations for i1 types. Widths of 8, 16 or 32 are equally treated as +/// legal to convert to, in order to open up more combining opportunities. +/// NOTE: this treats i8, i16 and i32 specially, due to them being so common +/// from frontend languages. bool InstCombiner::shouldChangeType(unsigned FromWidth, unsigned ToWidth) const { bool FromLegal = FromWidth == 1 || DL.isLegalInteger(FromWidth); bool ToLegal = ToWidth == 1 || DL.isLegalInteger(ToWidth); + // Convert to widths of 8, 16 or 32 even if they are not legal types. Only + // shrink types, to prevent infinite loops. + if (ToWidth < FromWidth && (ToWidth == 8 || ToWidth == 16 || ToWidth == 32)) + return true; + // If this is a legal integer from type, and the result would be an illegal // type, don't do the transformation. if (FromLegal && !ToLegal) |
