Commit Graph

4 Commits

Author SHA1 Message Date
Sam Kolton aff8341da2 [AMDGPU] SDWA: make pass global
Summary: Remove checks for basic blocks.

Reviewers: vpykhtin, rampitec, arsenm

Subscribers: kzhuravl, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye

Differential Revision: https://reviews.llvm.org/D31935

llvm-svn: 300040
2017-04-12 09:36:05 +00:00
Sam Kolton 9fa169601f [AMDGPU] Resubmit SDWA peephole: enable by default
Reviewers: vpykhtin, rampitec, arsenm

Subscribers: qcolombet, kzhuravl, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye

Differential Revision: https://reviews.llvm.org/D31671

llvm-svn: 299654
2017-04-06 15:03:28 +00:00
Sam Kolton 27e0f8bc72 [AMDGPU] SDWA Peephole: improve search for immediates in SDWA patterns
Previously compiler often extracted common immediates into specific register, e.g.:
```
%vreg0 = S_MOV_B32 0xff;
%vreg2 = V_AND_B32_e32 %vreg0, %vreg1
%vreg4 = V_AND_B32_e32 %vreg0, %vreg3
```
Because of this SDWA peephole failed to find SDWA convertible pattern. E.g. in previous example this could be converted into 2 SDWA src operands:
```
SDWA src: %vreg2 src_sel:BYTE_0
SDWA src: %vreg4 src_sel:BYTE_0
```
With this change peephole check if operand is either immediate or register that is copy of immediate.

llvm-svn: 299202
2017-03-31 11:42:43 +00:00
Sam Kolton f60ad58dad [ADMGPU] SDWA peephole optimization pass.
Summary:
First iteration of SDWA peephole.

This pass tries to combine several instruction into one SDWA instruction. E.g. it converts:
'''
    V_LSHRREV_B32_e32 %vreg0, 16, %vreg1
    V_ADD_I32_e32 %vreg2, %vreg0, %vreg3
    V_LSHLREV_B32_e32 %vreg4, 16, %vreg2
'''
Into:
'''
   V_ADD_I32_sdwa %vreg4, %vreg1, %vreg3 dst_sel:WORD_1 dst_unused:UNUSED_PAD src0_sel:WORD_1 src1_sel:DWORD
'''

Pass structure:
    1. Iterate over machine instruction in basic block and try to apply "SDWA patterns" to each of them. SDWA patterns match machine instruction into either source or destination SDWA operand. E.g. ''' V_LSHRREV_B32_e32 %vreg0, 16, %vreg1''' is matched to source SDWA operand '''%vreg1 src_sel:WORD_1'''.
    2. Iterate over found SDWA operands and find instruction that could be potentially coverted into SDWA. E.g. for source SDWA operand potential instruction are all instruction in this basic block that uses '''%vreg0'''
    3. Iterate over all potential instructions and check if they can be converted into SDWA.
    4. Convert instructions to SDWA.

This review contains basic implementation of SDWA peephole pass. This pass requires additional testing fot both correctness and performance (no performance testing done).
There are several ways this pass can be improved:
    1. Make this pass work on whole function not only basic block. As I can see this can be done right now without changes to pass.
    2. Introduce more SDWA patterns
    3. Introduce mnemonics to limit when SDWA patterns should apply

Reviewers: vpykhtin, alex-t, arsenm, rampitec

Subscribers: wdng, nhaehnle, mgorny

Differential Revision: https://reviews.llvm.org/D30038

llvm-svn: 298365
2017-03-21 12:51:34 +00:00