Mesa (main): aco: optimize abs(mul(a, b))

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Module: Mesa
Branch: main
Commit: 1804c21fb570285d90709010b746ed6812b42aa6
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=1804c21fb570285d90709010b746ed6812b42aa6

Author: Rhys Perry <pendingchaos02 at gmail.com>
Date:   Fri Jan 28 13:47:16 2022 +0000

aco: optimize abs(mul(a, b))

fossil-db (Sienna Cichlid):
Totals from 18 (0.01% of 134913) affected shaders:
CodeSize: 173924 -> 173852 (-0.04%)
Instrs: 33864 -> 33846 (-0.05%)
Latency: 122233 -> 122211 (-0.02%)
InvThroughput: 22482 -> 22462 (-0.09%)

Signed-off-by: Rhys Perry <pendingchaos02 at gmail.com>
Reviewed-by: Daniel Schürmann <daniel at schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14773>

---

 src/amd/compiler/aco_optimizer.cpp | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/amd/compiler/aco_optimizer.cpp b/src/amd/compiler/aco_optimizer.cpp
index 6f08dbfe930..537f3d4b1b9 100644
--- a/src/amd/compiler/aco_optimizer.cpp
+++ b/src/amd/compiler/aco_optimizer.cpp
@@ -3482,8 +3482,8 @@ combine_instruction(opt_ctx& ctx, aco_ptr<Instruction>& instr)
     * The various comparison optimizations also currently only work with 32-bit
     * floats. */
 
-   /* neg(mul(a, b)) -> mul(neg(a), b) */
-   if (ctx.info[instr->definitions[0].tempId()].is_neg() &&
+   /* neg(mul(a, b)) -> mul(neg(a), b), abs(mul(a, b)) -> mul(abs(a), abs(b)) */
+   if ((ctx.info[instr->definitions[0].tempId()].label & (label_neg | label_abs)) &&
        ctx.uses[instr->operands[1].tempId()] == 1) {
       Temp val = ctx.info[instr->definitions[0].tempId()].temp;
 
@@ -3502,10 +3502,10 @@ combine_instruction(opt_ctx& ctx, aco_ptr<Instruction>& instr)
           ctx.fp_mode.preserve_signed_zero_inf_nan32)
          return;
 
-      /* convert to mul(neg(a), b) */
+      /* convert to mul(neg(a), b), mul(abs(a), abs(b)) or mul(neg(abs(a)), abs(b)) */
       ctx.uses[mul_instr->definitions[0].tempId()]--;
       Definition def = instr->definitions[0];
-      /* neg(abs(mul(a, b))) -> mul(neg(abs(a)), abs(b)) */
+      bool is_neg = ctx.info[instr->definitions[0].tempId()].is_neg();
       bool is_abs = ctx.info[instr->definitions[0].tempId()].is_abs();
       instr.reset(
          create_instruction<VOP3_instruction>(mul_instr->opcode, asVOP3(Format::VOP2), 2, 1));
@@ -3525,7 +3525,7 @@ combine_instruction(opt_ctx& ctx, aco_ptr<Instruction>& instr)
          new_mul.neg[0] = new_mul.neg[1] = false;
          new_mul.abs[0] = new_mul.abs[1] = true;
       }
-      new_mul.neg[0] ^= true;
+      new_mul.neg[0] ^= is_neg;
       new_mul.clamp = false;
 
       ctx.info[instr->definitions[0].tempId()].set_mul(instr.get());