[Mesa-dev] [RFC 2/7] nir: coverity sign-extension fix

Rob Clark robdclark at gmail.com
Wed May 18 15:54:10 UTC 2016


From: Rob Clark <robclark at freedesktop.org>

Not 100% sure, but I think being an unsigned literal will help:

CID 1358505 (#1 of 1): Unintended sign extension
(SIGN_EXTENSION)sign_extension: Suspicious implicit sign extension:
load1->def.num_components with type unsigned char (8 bits, unsigned) is
promoted in load1->def.num_components * (load1->def.bit_size / 8) to
type int (32 bits, signed), then sign-extended to type unsigned long (64
bits, unsigned). If load1->def.num_components * (load1->def.bit_size /
8) is greater than 0x7FFFFFFF, the upper bits of the result will all be
1.
---
 src/compiler/nir/nir_instr_set.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/compiler/nir/nir_instr_set.c b/src/compiler/nir/nir_instr_set.c
index fe312a0..f93ec9d 100644
--- a/src/compiler/nir/nir_instr_set.c
+++ b/src/compiler/nir/nir_instr_set.c
@@ -334,7 +334,7 @@ nir_instrs_equal(const nir_instr *instr1, const nir_instr *instr2)
          return false;
 
       return memcmp(load1->value.f32, load2->value.f32,
-                    load1->def.num_components * (load1->def.bit_size / 8)) == 0;
+                    load1->def.num_components * (load1->def.bit_size / 8u)) == 0;
    }
    case nir_instr_type_phi: {
       nir_phi_instr *phi1 = nir_instr_as_phi(instr1);
-- 
2.5.5



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