1From 9cd614dd5481a4fdf552effac4820f51a10092c7 Mon Sep 17 00:00:00 2001
2From: =?UTF-8?q?Mika=20V=C3=A4in=C3=B6l=C3=A4?=
3 <33728696+mvainola@users.noreply.github.com>
4Date: Wed, 7 Apr 2021 13:12:17 +0300
5Subject: [PATCH] Workaround for GCC 11 uninit variable warnings (#946)
6
7Building Amber with GCC 11.0.1 produces some uninitialized variable
8warnings. This commit works around them by replacing
9reinterpret_cast with memcpy when type punning unsigned integers to
10floats.
11
12Upstream-Status: Backport [https://github.com/google/amber/commit/aa69a0ac23ea7f68dd32bbef210546a5d84c1734]
13---
14 src/float16_helper.cc | 22 ++++++++++++++++------
15 1 file changed, 16 insertions(+), 6 deletions(-)
16
17diff --git a/src/float16_helper.cc b/src/float16_helper.cc
18index 617bd72..5cb35e7 100644
19--- a/src/float16_helper.cc
20+++ b/src/float16_helper.cc
21@@ -15,6 +15,7 @@
22 #include "src/float16_helper.h"
23
24 #include <cassert>
25+#include <cstring>
26
27 // Float10
28 // | 9 8 7 6 5 | 4 3 2 1 0 |
29@@ -75,8 +76,11 @@ float HexFloat16ToFloat(const uint8_t* value) {
30   }
31
32   uint32_t hex = sign | exponent | mantissa;
33-  float* hex_float = reinterpret_cast<float*>(&hex);
34-  return *hex_float;
35+  float hex_float;
36+  static_assert((sizeof(uint32_t) == sizeof(float)),
37+                "sizeof(uint32_t) != sizeof(float)");
38+  memcpy(&hex_float, &hex, sizeof(float));
39+  return hex_float;
40 }
41
42 // Convert float |value| whose size is 11 bits to 32 bits float
43@@ -89,8 +93,11 @@ float HexFloat11ToFloat(const uint8_t* value) {
44   uint32_t mantissa = (static_cast<uint32_t>(value[0]) & 0x3f) << 17U;
45
46   uint32_t hex = exponent | mantissa;
47-  float* hex_float = reinterpret_cast<float*>(&hex);
48-  return *hex_float;
49+  float hex_float;
50+  static_assert((sizeof(uint32_t) == sizeof(float)),
51+                "sizeof(uint32_t) != sizeof(float)");
52+  memcpy(&hex_float, &hex, sizeof(float));
53+  return hex_float;
54 }
55
56 // Convert float |value| whose size is 10 bits to 32 bits float
57@@ -103,8 +110,11 @@ float HexFloat10ToFloat(const uint8_t* value) {
58   uint32_t mantissa = (static_cast<uint32_t>(value[0]) & 0x1f) << 18U;
59
60   uint32_t hex = exponent | mantissa;
61-  float* hex_float = reinterpret_cast<float*>(&hex);
62-  return *hex_float;
63+  float hex_float;
64+  static_assert((sizeof(uint32_t) == sizeof(float)),
65+                "sizeof(uint32_t) != sizeof(float)");
66+  memcpy(&hex_float, &hex, sizeof(float));
67+  return hex_float;
68 }
69
70 }  // namespace
71--
722.31.1
73
74