intel/debug: Add a debug flag to force software fp64

Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/intel/common/gen_debug.c

@@ -85,6 +85,7 @@ static const struct debug_control debug_control[] = {
    { "nohiz",       DEBUG_NO_HIZ },
    { "color",       DEBUG_COLOR },
    { "reemit",      DEBUG_REEMIT },
+   { "soft64",      DEBUG_SOFT64 },
    { NULL,    0 }
 };
 

src/intel/common/gen_debug.h

@@ -83,6 +83,7 @@ extern uint64_t INTEL_DEBUG;
 #define DEBUG_NO_HIZ              (1ull << 39)
 #define DEBUG_COLOR               (1ull << 40)
 #define DEBUG_REEMIT              (1ull << 41)
+#define DEBUG_SOFT64              (1ull << 42)
 
 /* These flags are not compatible with the disk shader cache */
 #define DEBUG_DISK_CACHE_DISABLE_MASK DEBUG_SHADER_TIME
@@ -90,7 +91,7 @@ extern uint64_t INTEL_DEBUG;
 /* These flags may affect program generation */
 #define DEBUG_DISK_CACHE_MASK \
    (DEBUG_NO16 | DEBUG_NO_DUAL_OBJECT_GS | DEBUG_NO8 |  DEBUG_SPILL_FS | \
-   DEBUG_SPILL_VEC4 | DEBUG_NO_COMPACTION | DEBUG_DO32)
+   DEBUG_SPILL_VEC4 | DEBUG_NO_COMPACTION | DEBUG_DO32 | DEBUG_SOFT64)
 
 #ifdef HAVE_ANDROID_PLATFORM
 #define LOG_TAG "INTEL-MESA"

src/intel/compiler/brw_compiler.c

@@ -159,7 +159,7 @@ brw_compiler_create(void *mem_ctx, const struct gen_device_info *devinfo)
       nir_lower_dround_even |
       nir_lower_dmod;
 
-   if (!devinfo->has_64bit_types) {
+   if (!devinfo->has_64bit_types || (INTEL_DEBUG & DEBUG_SOFT64)) {
       int64_options |= nir_lower_mov64 |
                        nir_lower_icmp64 |
                        nir_lower_iadd64 |