[llvm] [RISCV] Add a pass to remove ADDI by reassociating to fold into load/store address. (PR #127151)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

Compile-time and size measurements on llvm-test-suite (rv64gc):
```
dtcxzyw at dtcxzyw:~/WorkSpace/Projects/compilers/tmp/llvm-test-suite$ python3 utils/compare.py -m size..text ../baseline.json ../new.json 
Tests: 320
Metric: size..text

Program                                       size..text               
                                              baseline   new      diff 
MultiSourc...ity-rijndael/security-rijndael   12414.00   12726.00  2.5%
MultiSourc...marks/VersaBench/ecbdes/ecbdes    6158.00    6212.00  0.9%
SingleSour...ce/Benchmarks/Misc/ReedSolomon    4684.00    4696.00  0.3%
MultiSourc...reeBench/pcompress2/pcompress2    4240.00    4242.00  0.0%
MultiSource/Benchmarks/McCat/18-imp/imp        9302.00    9304.00  0.0%
MultiSourc...VC/Searching-flt/Searching-flt   22700.00   22700.00  0.0%
SingleSour...enchmarks/Misc-C++/oopack_v1p8    2746.00    2746.00  0.0%
SingleSource/Benchmarks/Misc/evalloop           652.00     652.00  0.0%
SingleSource/Benchmarks/Misc/dt                 422.00     422.00  0.0%
SingleSour...chmarks/Misc-C++/stepanov_v1p2    4252.00    4252.00  0.0%
SingleSour...ks/Misc-C++/stepanov_container   12930.00   12930.00  0.0%
SingleSource/Benchmarks/Misc-C++/bigfib        5750.00    5750.00  0.0%
SingleSour...enchmarks/Misc-C++/mandel-text     500.00     500.00  0.0%
SingleSource/Benchmarks/Misc/ffbench           1752.00    1752.00  0.0%
SingleSour...rks/Misc-C++/Large/sphereflake    4082.00    4082.00  0.0%
                           Geomean difference                     -0.1%
          size..text                           
run         baseline            new        diff
count  320.000000     320.000000     320.000000
mean   40075.862500   39984.812500  -0.001049  
std    93336.449929   93034.162808   0.005909  
min    188.000000     188.000000    -0.078735  
25%    1236.500000    1236.500000   -0.000236  
50%    3788.000000    3788.000000    0.000000  
75%    25440.000000   25440.000000   0.000000  
max    639140.000000  638774.000000  0.025133  
dtcxzyw at dtcxzyw:~/WorkSpace/Projects/compilers/tmp/llvm-test-suite$ python3 utils/compare.py -m compile_time ../baseline.json ../new.json 
Tests: 320
Metric: compile_time

Program                                       compile_time             
                                              baseline     new    diff 
MultiSourc...hmarks/Rodinia/hotspot/hotspot     0.30         0.38 28.8%
SingleSour...h/stencils/seidel-2d/seidel-2d     0.18         0.23 25.1%
SingleSour...h/stencils/jacobi-2d/jacobi-2d     0.21         0.25 23.8%
MultiSourc...nch/mpeg2/mpeg2dec/mpeg2decode     2.80         3.45 23.3%
MultiSourc...e/Applications/obsequi/Obsequi     2.46         3.03 23.1%
MultiSourc.../Rodinia/pathfinder/pathfinder     0.30         0.37 21.4%
MultiSourc...arks/DOE-ProxyApps-C/CoMD/CoMD     2.28         2.74 20.6%
MultiSourc...roxyApps-C/SimpleMOC/SimpleMOC     2.02         2.43 20.5%
MultiSourc...OE-ProxyApps-C/miniGMG/miniGMG     2.44         2.93 20.1%
MultiSourc...e/Benchmarks/MallocBench/gs/gs    10.12        12.07 19.3%
MultiSource/Applications/lua/lua                7.23         8.61 19.1%
MultiSourc...basicmath/automotive-basicmath     0.47         0.56 18.6%
MultiSourc...hmarks/MallocBench/cfrac/cfrac     2.80         3.28 17.4%
MultiSourc...enchmarks/mafft/pairlocalalign    14.23        16.60 16.7%
MultiSource/Benchmarks/nbench/nbench            1.97         2.30 16.7%
                           Geomean difference                     -4.0%
      compile_time                        
run       baseline         new        diff
count  320.000000   320.000000  284.000000
mean   2.955303     2.945959   -0.034530  
std    9.903914     9.888480    0.107569  
min    0.000000     0.000000   -0.232461  
25%    0.160575     0.148825   -0.113482  
50%    0.412650     0.393900   -0.030871  
75%    1.508075     1.325575    0.022703  
max    136.916200   136.221800  0.287965  

```

https://github.com/llvm/llvm-project/pull/127151