gentoo-overlay/dev-python/numpy/files/numpy-1.20.2-fix-popcnt-detection.patch

https://github.com/numpy/numpy/pull/19074
https://bugs.gentoo.org/788184

From 8dc768964b5578a8aa9db1ef2c55134a00731e10 Mon Sep 17 00:00:00 2001
From: Carl Michal <michal@physics.ubc.ca>
Date: Sat, 22 May 2021 20:43:10 -0700
Subject: [PATCH 1/2] Fix compile-time test of POPCNT

The compile-time test of POPCNT, cpu_popcnt.c produced code that would
execute without error even if the machine didn't support the popcnt
instruction. This patch attempts to use popcnt on random numbers so the
compiler can't substitute the answer at compile time.
---
 numpy/distutils/checks/cpu_popcnt.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/numpy/distutils/checks/cpu_popcnt.c b/numpy/distutils/checks/cpu_popcnt.c
index e6a80fb40be4..f6c785dd2a97 100644
--- a/numpy/distutils/checks/cpu_popcnt.c
+++ b/numpy/distutils/checks/cpu_popcnt.c
@@ -4,20 +4,26 @@
     #include <popcntintrin.h>
 #endif
 
+#include <stdlib.h>
+
 int main(void)
 {
     long long a = 0;
     int b;
+    
+    a = random();
+    b = random();
+      
 #ifdef _MSC_VER
     #ifdef _M_X64
-    a = _mm_popcnt_u64(1);
+    a = _mm_popcnt_u64(a);
     #endif
-    b = _mm_popcnt_u32(1);
+    b = _mm_popcnt_u32(b);
 #else
     #ifdef __x86_64__
-    a = __builtin_popcountll(1);
+    a = __builtin_popcountll(a);
     #endif
-    b = __builtin_popcount(1);
+    b = __builtin_popcount(b);
 #endif
     return (int)a + b;
 }

From 52d5fe1ede45083d0783c3e2bbaee5c44df9d553 Mon Sep 17 00:00:00 2001
From: Carl Michal <michal@physics.ubc.ca>
Date: Sun, 23 May 2021 08:24:52 -0700
Subject: [PATCH 2/2] Change fix of cpu_popcnt.c to use
 _mm_popcnt_u64/_mm_popcnt_u32 on GCC

_builtin_popcount is always available, so the compile-time check always
succeeds.
---
 numpy/distutils/checks/cpu_popcnt.c | 26 ++++++++------------------
 1 file changed, 8 insertions(+), 18 deletions(-)

diff --git a/numpy/distutils/checks/cpu_popcnt.c b/numpy/distutils/checks/cpu_popcnt.c
index f6c785dd2a97..540c98dab05d 100644
--- a/numpy/distutils/checks/cpu_popcnt.c
+++ b/numpy/distutils/checks/cpu_popcnt.c
@@ -4,26 +4,16 @@
     #include <popcntintrin.h>
 #endif
 
-#include <stdlib.h>
-
-int main(void)
+int main(int argc, char **argv)
 {
-    long long a = 0;
-    int b;
-    
-    a = random();
-    b = random();
-      
-#ifdef _MSC_VER
-    #ifdef _M_X64
+    // To make sure popcnt instructions are generated
+    // and been tested against the assembler
+    unsigned long long a = *((unsigned long long*)argv[argc-1]);
+    unsigned int b = *((unsigned int*)argv[argc-2]);
+
+#if defined(_M_X64) || defined(__x86_64__)    
     a = _mm_popcnt_u64(a);
-    #endif
-    b = _mm_popcnt_u32(b);
-#else
-    #ifdef __x86_64__
-    a = __builtin_popcountll(a);
-    #endif
-    b = __builtin_popcount(b);
 #endif
+    b = _mm_popcnt_u32(b);
     return (int)a + b;
 }