search for: g_unmerge_value

Hi, I’m trying to handle some vector operations with splitting/scalarization and keep running into similar sorts of issues which are making me question the intended function of the various legalization operations (particularly G_MERGE_VALUES/G_UNMERGE_VALUES, but also G_EXTRACT/G_INSERT and conversion instructions) and what the contract between the legalizer and selector actually is. For scalar values, things seem clearer, but I’m still confused. The AArch64 selector code seems content to allow strange sized values in the source of G_EXTRACT/G_SEXT e...

Hi, Mips32 has 64 bit floating point instructions, while i64 instructions have to be emulated with i32 instructions. This means that G_LOAD should be custom legalized for s64 integer value, and be legal for s64 floating point value. There are also other generic instructions with the same problem: G_STORE, G_SELECT, G_EXTRACT, and G_INSERT. There are also other configurations where integer

...as following your discussion on D75086 regarding declaring types as legal even if they are smaller than the actual register class (e.g. s16 and gpr32). We are working on a backend which only has 32 and 64-bit registers and we recently had a problem regarding exactly this where we had to declare G_UNMERGE_VALUES and G_MERGE_VALUES with a smaller type of <s32 as legal, even though we don't have a register class that matches and instruction selection implicitly sign extends them to s32. The reasoning was that for example in the case of G_UNMERGE_VALUES, the legalizer widens the source type when w...

Hi all, recently when working with GlobalISel we have often encountered cases in the legalizer where 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...

...I was following your discussion on D75086 regarding declaring types as legal even if they are smaller than the actual register class (e.g. s16 and gpr32). We are working on a backend which only has 32 and 64-bit registers and we recently had a problem regarding exactly this where we had to declare G_UNMERGE_VALUES and G_MERGE_VALUES with a smaller type of <s32 as legal, even though we don't have a register class that matches and instruction selection implicitly sign extends them to s32. The reasoning was that for example in the case of G_UNMERGE_VALUES, the legalizer widens the source type when widen...

Hi, I’m looking at RegBankSelect’s partially implemented support for deciding to split a value between multiple registers and I’m wondering if it’s actually intended to solve the problem I’m trying to use it for. RegisterBankInfo.h has this example mapping table: /// E.g., /// Let say we have a 32-bit add and a <2 x 32-bit> vadd. We /// can expand the /// <2 x 32-bit> add into

...24, 2020, at 12:24, Dominik Montada via llvm-dev <llvm-dev at lists.llvm.org> wrote: >> >> Hi all, >> >> recently when working with GlobalISel we have often encountered cases in the legalizer where 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 th...

Hi all, first of all thanks to Matt for hosting the round table yesterday and to everyone else for their time and the valuable discussions. As promised in the chat yesterday, here is the email regarding the legalizer / artifact combiner issue we talked about. I will send a separate email regarding the regbankselect discussion. In case someone on the list didn't attend the round table