Follow-up to #157682
When we know that one operand of an addition is a constant, we might was well put it on the right-hand side and avoid the work to canonicalize it in a later pass.
[AMDGPU] Treat GEP offsets as signed in AMDGPUPromoteAlloca AMDGPUPromoteAlloca can transform i32 GEP offsets that operate on allocas into i64 extractelement indices. Before this patch, negative GEP offsets would be zero-extended, leading to wrong extractelement indices with values around (2**32-1). This fixes failing LlvmLibcCharacterConverterUTF32To8Test tests for AMDGPU.
Increase promote-alloca-to-vector-max-regs to 32 from 16. This restores default promotion of 16 x double which was disabled by #127973. Fixes SWDEV-525817.
Use a function attribute (amdgpu-dynamic-vgpr) instead of a subtarget feature, as requested in #130030.
This is only run in the middle end with the new pass manager now, so garbage collect the old PM version.
Reverts llvm/llvm-project#143784 Patch fails some internal tests. Will investigate more thoroughly before attempting to remerge.
Extends the `amdgpu-promote-alloca-to-vector` pass to also promote aggregate types whose elements are all the same type to vector registers. The motivation for this extension was to account for IR generated by the frontend containing several singleton struct types containing vectors or vector-like elements, though the implementation is strictly more general.
Supports the `nestedGEP`pattern that appears when an alloca is first indexed as an array element and then shifted with a byte‑offset GEP: ```llvm %SortedFragments = alloca [10 x <2 x i32>], addrspace(5), align 8 %row = getelementptr [10 x <2 x i32>], ptr addrspace(5) %SortedFragments, i32 0, i32 %j %elt1 = getelementptr i8, ptr addrspace(5) %row, i32 4 %val = load i32, ptr addrspace(5) %elt1 ``` The pass folds the two levels of addressing into a single vector lane index and keeps the whole object in a VGPR: ```llvm %vec = freeze <20 x i32> poison ; alloca promote <20 x i32> %idx0 = mul i32 %j, 2 ; j * 2 %idx = add i32 %idx0, 1 ; j * 2 + 1 %val = extractelement <20 x i32> %vec, i32 %idx ``` This eliminates the scratch read.