commit 1ef2e250fc36d862573cc5e92f04b1d0e2d89867
author Shahbaz Youssefi <ShabbyX@gmail.com> Fri Jul 03 15:42:53 2020 -0400
committer Shahbaz Youssefi <ShabbyX@gmail.com> Fri Jul 31 12:44:49 2020 -0400
tree f964a5dac59ec0a1dcfe76fd9ebec3dc5bf0b700
parent 7ab4564696a79243a48d6d5169eafdfb117e44fc

Use GLSLANG_ANGLE to strip features to what ANGLE requires

This change strips a few features similar to GLSLANG_WEB but doesn't
remove every detail like the latter.  It also hardcodes profile/version
to core/450.

In particular, TBuiltIns::initialize is specialized to remove most of
what is not supported or won't be supported by ANGLE.  The result of
this function is parsed with TParseContext::parseShaderStrings which is
a performance bottleneck.

This change shaves about 300KB off of ANGLE's binary size and reduces
the cost of SetupBuiltinSymbolTable to nearly a sixth.

Signed-off-by: Shahbaz Youssefi <ShabbyX@gmail.com>

BUILD.gn

diff --git a/BUILD.gn b/BUILD.gn
index 7242b6f..9525b5d 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -109,7 +109,6 @@
       "SPIRV/SpvBuilder.cpp",
       "SPIRV/SpvBuilder.h",
       "SPIRV/SpvPostProcess.cpp",
-      "SPIRV/SpvTools.cpp",
       "SPIRV/SpvTools.h",
       "SPIRV/bitutils.h",
       "SPIRV/disassemble.cpp",
@@ -208,8 +207,12 @@
 
     defines = []
     if (invoker.enable_opt) {
+      sources += [ "SPIRV/SpvTools.cpp" ]
       defines += [ "ENABLE_OPT=1" ]
     }
+    if (invoker.is_angle) {
+      defines += [ "GLSLANG_ANGLE" ]
+    }
 
     if (is_win) {
       sources += [ "glslang/OSDependent/Windows/ossource.cpp" ]
@@ -257,11 +260,13 @@
 glslang_sources_common("glslang_lib_sources") {
   enable_opt = !glslang_angle
   enable_hlsl = !glslang_angle
+  is_angle = glslang_angle
 }
 
 glslang_sources_common("glslang_sources") {
   enable_opt = true
   enable_hlsl = true
+  is_angle = false
 }
 
 source_set("glslang_default_resource_limits_sources") {