search for: widenscalartonextpow2

...gt;> b) Is the plan to sometimes let s1 as legal type and ignore it later? > I'm not sure what you mean here > For example lets look at AArch64 G_SELECT:   getActionDefinitionsBuilder(G_SELECT)       .legalFor({{s32, s1}, {s64, s1}, {p0, s1}})       .clampScalar(0, s32, s64)       .widenScalarToNextPow2(0); In this case LLT of operand 1 (s1) in G_SELECT has size 1, and corresponding register class in selected instruction has size 32 (that is $src1 in AArch64::ANDSWri, it has GPR32 regsiter class). For that reason s1 is practically ignored and silently converted to s32. We could get similar resu...

...ould not be narrowed because the narrowing code relies on G_UNMERGE_VALUES and therefore requires the source type to be a multiple of the narrow type. Often times these instructions can be widened without any problem to a fitting type. >> >> This has us writing legalization rules like `.widenScalarToNextPow2(0, /*MinSize*/ 32).maxScalar(0, s32)` instead of the much simpler `.clampScalar(0, s32 ,s32)`. >> >> Although this works and has the desired effect, we feel like that such a rule requires internal knowledge of the legalizer, which can change at any point in the future. Ideally we would...

...instructions could not be narrowed because the narrowing code relies on G_UNMERGE_VALUES and therefore requires the source type to be a multiple of the narrow type. Often times these instructions can be widened without any problem to a fitting type. This has us writing legalization rules like `.widenScalarToNextPow2(0, /*MinSize*/ 32).maxScalar(0, s32)` instead of the much simpler `.clampScalar(0, s32 ,s32)`. Although this works and has the desired effect, we feel like that such a rule requires internal knowledge of the legalizer, which can change at any point in the future. Ideally we would only want to...

Hello, I am developing GlobalISel for MIPS. I have a few questions and observations about defining legality of generic instruction and also possible combining of instructions and artifacts in pre/post legalizer combiner or elsewhere (e.g. in some sort of instruction-select patterns). I look at legality as "If generic instruction can be selected into machine instruction, it is legal".