From 41cd8836d785c79381764e7de59319f87959a5cf Mon Sep 17 00:00:00 2001
From: Alistair Francis <alistair@alistair23.me>
Date: Thu, 14 Nov 2019 09:06:02 -0800
Subject: [PATCH] Revert "mesa: Enable asm unconditionally, now that
 gen_matypes is gone."

This reverts commit 20294dceebc23236e33b22578245f7e6f41b6997.

Upstream-Status: Inappropriate [configuration]
Signed-off-by: Alistair Francis <alistair@alistair23.me>

---
 meson.build       | 94 ++++++++++++++++++++++++++++++-----------------
 meson_options.txt |  6 +++
 2 files changed, 67 insertions(+), 33 deletions(-)

diff --git a/meson.build b/meson.build
index 62864c6..b53be8d 100644
--- a/meson.build
+++ b/meson.build
@@ -49,6 +49,7 @@ with_vulkan_icd_dir = get_option('vulkan-icd-dir')
 with_tests = get_option('build-tests')
 with_valgrind = get_option('valgrind')
 with_libunwind = get_option('libunwind')
+with_asm = get_option('asm')
 with_glx_read_only_text = get_option('glx-read-only-text')
 with_glx_direct = get_option('glx-direct')
 with_osmesa = get_option('osmesa')
@@ -1093,41 +1094,68 @@ dep_ws2_32 = cc.find_library('ws2_32', required : with_platform_windows)
 
 # TODO: shared/static? Is this even worth doing?
 
+# When cross compiling we generally need to turn off the use of assembly,
+# because mesa's assembly relies on building an executable for the host system,
+# and running it to get information about struct sizes. There is at least one
+# case of cross compiling where we can use asm, and that's x86_64 -> x86 when
+# host OS == build OS, since in that case the build machine can run the host's
+# binaries.
+if with_asm and meson.is_cross_build()
+  if build_machine.system() != host_machine.system()
+    # TODO: It may be possible to do this with an exe_wrapper (like wine).
+    message('Cross compiling from one OS to another, disabling assembly.')
+    with_asm = false
+  elif not (build_machine.cpu_family().startswith('x86') and host_machine.cpu_family() == 'x86')
+    # FIXME: Gentoo always sets -m32 for x86_64 -> x86 builds, resulting in an
+    # x86 -> x86 cross compile. We use startswith rather than == to handle this
+    # case.
+    # TODO: There may be other cases where the 64 bit version of the
+    # architecture can run 32 bit binaries (aarch64 and armv7 for example)
+    message('''
+      Cross compiling to different architectures, and the host cannot run
+      the build machine's binaries. Disabling assembly.
+    ''')
+    with_asm = false
+  endif
+endif
+
 with_asm_arch = ''
-if host_machine.cpu_family() == 'x86'
-  if system_has_kms_drm or host_machine.system() == 'gnu'
-    with_asm_arch = 'x86'
-    pre_args += ['-DUSE_X86_ASM', '-DUSE_MMX_ASM', '-DUSE_3DNOW_ASM',
-                 '-DUSE_SSE_ASM']
-
-    if with_glx_read_only_text
-      pre_args += ['-DGLX_X86_READONLY_TEXT']
+if with_asm
+  if host_machine.cpu_family() == 'x86'
+    if system_has_kms_drm or host_machine.system() == 'gnu'
+      with_asm_arch = 'x86'
+      pre_args += ['-DUSE_X86_ASM', '-DUSE_MMX_ASM', '-DUSE_3DNOW_ASM',
+                   '-DUSE_SSE_ASM']
+
+      if with_glx_read_only_text
+         pre_args += ['-DGLX_X86_READONLY_TEXT']
+      endif
+    endif
+  elif host_machine.cpu_family() == 'x86_64'
+    if system_has_kms_drm
+      with_asm_arch = 'x86_64'
+      pre_args += ['-DUSE_X86_64_ASM']
+    endif
+  elif host_machine.cpu_family() == 'arm'
+    if system_has_kms_drm
+      with_asm_arch = 'arm'
+      pre_args += ['-DUSE_ARM_ASM']
+    endif
+  elif host_machine.cpu_family() == 'aarch64'
+    if system_has_kms_drm
+      with_asm_arch = 'aarch64'
+      pre_args += ['-DUSE_AARCH64_ASM']
+    endif
+  elif host_machine.cpu_family() == 'sparc64'
+    if system_has_kms_drm
+      with_asm_arch = 'sparc'
+      pre_args += ['-DUSE_SPARC_ASM']
+    endif
+  elif host_machine.cpu_family().startswith('ppc64') and host_machine.endian() == 'little'
+    if system_has_kms_drm
+      with_asm_arch = 'ppc64le'
+      pre_args += ['-DUSE_PPC64LE_ASM']
     endif
-  endif
-elif host_machine.cpu_family() == 'x86_64'
-  if system_has_kms_drm
-    with_asm_arch = 'x86_64'
-    pre_args += ['-DUSE_X86_64_ASM']
-  endif
-elif host_machine.cpu_family() == 'arm'
-  if system_has_kms_drm
-    with_asm_arch = 'arm'
-    pre_args += ['-DUSE_ARM_ASM']
-  endif
-elif host_machine.cpu_family() == 'aarch64'
-  if system_has_kms_drm
-    with_asm_arch = 'aarch64'
-    pre_args += ['-DUSE_AARCH64_ASM']
-  endif
-elif host_machine.cpu_family() == 'sparc64'
-  if system_has_kms_drm
-    with_asm_arch = 'sparc'
-    pre_args += ['-DUSE_SPARC_ASM']
-  endif
-elif host_machine.cpu_family().startswith('ppc64') and host_machine.endian() == 'little'
-  if system_has_kms_drm
-    with_asm_arch = 'ppc64le'
-    pre_args += ['-DUSE_PPC64LE_ASM']
   endif
 endif
 
diff --git a/meson_options.txt b/meson_options.txt
index 700c34c..62e8472 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -241,6 +241,12 @@ option(
   value : false,
   description : 'Enable GLVND support.'
 )
+option(
+  'asm',
+  type : 'boolean',
+  value : true,
+  description : 'Build assembly code if possible'
+)
 option(
    'glx-read-only-text',
    type : 'boolean',
