[Mesa-dev] [PATCH v2] nir: fix interger divide by zero crash during constant folding

Timothy Arceri tarceri at itsqueeze.com
Wed Feb 28 03:33:55 UTC 2018


>From the GLSL 4.60 spec Section 5.9 (Expressions):

   "Dividing by zero does not cause an exception but does result in
    an unspecified value."

Fixes: 89285e4d47a6 "nir: add new constant folding infrastructure"

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105271
---
 src/compiler/nir/nir_opcodes.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/compiler/nir/nir_opcodes.py b/src/compiler/nir/nir_opcodes.py
index 278562b2bd..97da4db28f 100644
--- a/src/compiler/nir/nir_opcodes.py
+++ b/src/compiler/nir/nir_opcodes.py
@@ -404,8 +404,8 @@ binop("umul_high", tuint32, commutative,
       "(uint32_t)(((uint64_t) src0 * (uint64_t) src1) >> 32)")
 
 binop("fdiv", tfloat, "", "src0 / src1")
-binop("idiv", tint, "", "src0 / src1")
-binop("udiv", tuint, "", "src0 / src1")
+binop("idiv", tint, "", "src1 == 0 ? 0 : (src0 / src1)")
+binop("udiv", tuint, "", "src1 == 0 ? 0 : (src0 / src1)")
 
 # returns a boolean representing the carry resulting from the addition of
 # the two unsigned arguments.
-- 
2.14.3



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