[Mesa-dev] [PATCH 2/8] radeonsi: do EarlyCSEMemSSA LLVM pass

[Marek Olšák]

From: Marek Olšák <marek.olsak at amd.com>

so that LLVM IR looks like CSE has been run on it. It's also recommended
by the instruction combining pass.

This also fixes:
- GL45-CTS.arrays_of_arrays_gl.InteractionFunctionCalls2 (crash)
- piglit/spec/arb_shader_ballot/execution/fs-readFirstInvocation-uint-loop (fail)

The code size decrease is positive, the register usage isn't. There is
a decrease in VGPR spilling for Tomb Raider, but increase in DiRT Showdown
and GRID Autosport.

EarlyCSEMemSSA has a -0.01% change in code size compared EarlyCSE.

SGPRS: 1935420 -> 1938076 (0.14 %)
VGPRS: 1645504 -> 1645988 (0.03 %)
Spilled SGPRs: 2493 -> 2651 (6.34 %)
Spilled VGPRs: 107 -> 115 (7.48 %)
Private memory VGPRs: 1332 -> 1332 (0.00 %)
Scratch size: 1512 -> 1516 (0.26 %) dwords per thread
Code Size: 61981592 -> 61890012 (-0.15 %) bytes
Max Waves: 371847 -> 371798 (-0.01 %)
---
 src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c b/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
index 1f8e913..802e2b9 100644
--- a/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
+++ b/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
@@ -1444,20 +1444,22 @@ void si_llvm_optimize_module(struct si_shader_context *ctx)
 	LLVMAddAlwaysInlinerPass(gallivm->passmgr);
 
 	/* This pass should eliminate all the load and store instructions */
 	LLVMAddPromoteMemoryToRegisterPass(gallivm->passmgr);
 
 	/* Add some optimization passes */
 	LLVMAddScalarReplAggregatesPass(gallivm->passmgr);
 	LLVMAddLICMPass(gallivm->passmgr);
 	LLVMAddAggressiveDCEPass(gallivm->passmgr);
 	LLVMAddCFGSimplificationPass(gallivm->passmgr);
+	/* This is recommended by the instruction combining pass. */
+	LLVMAddEarlyCSEMemSSAPass(gallivm->passmgr);
 	LLVMAddInstructionCombiningPass(gallivm->passmgr);
 
 	/* Run the pass */
 	LLVMRunPassManager(gallivm->passmgr, ctx->gallivm.module);
 
 	LLVMDisposeBuilder(gallivm->builder);
 	LLVMDisposePassManager(gallivm->passmgr);
 	gallivm_dispose_target_library_info(target_library_info);
 }
 
-- 
2.7.4