From: Timur Kristóf <timur.kristof@gmail.com>
Date: Sat, 22 Aug 2020 18:45:54 +0000 (+0200)
Subject: aco: Fix convert_to_SDWA when instruction has 3 operands.
X-Git-Url: https://git.libre-soc.org/?p=mesa.git;a=commitdiff_plain;h=f820dde201f82763b5165dfe6516f20e9c80795b

aco: Fix convert_to_SDWA when instruction has 3 operands.

Previously, when the instruction had 3 operands, this would cause
possible corruption because of writing to sdwa->sel[2].
This was noticed thanks to GCC 10's -Wstringop-overflow warning.

Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6436>
---

diff --git a/src/amd/compiler/aco_ir.cpp b/src/amd/compiler/aco_ir.cpp
index 801fbc68616..b594b2824e9 100644
--- a/src/amd/compiler/aco_ir.cpp
+++ b/src/amd/compiler/aco_ir.cpp
@@ -238,6 +238,10 @@ aco_ptr<Instruction> convert_to_SDWA(chip_class chip, aco_ptr<Instruction>& inst
    }
 
    for (unsigned i = 0; i < instr->operands.size(); i++) {
+      /* SDWA only uses operands 0 and 1. */
+      if (i >= 2)
+         break;
+
       switch (instr->operands[i].bytes()) {
       case 1:
          sdwa->sel[i] = sdwa_ubyte;