radeonsi: Add debug option to enable LLVM GlobalISel (v2)

R600_DEBUG=gisel will tell LLVM to use GlobalISel rather than
SelectionDAG for instruction selection.

v2: mareko: move the helper to src/amd/common

Signed-off-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Tom Stellard <tstellar@redhat.com>

diff --git a/src/amd/common/ac_llvm_helper.cpp b/src/amd/common/ac_llvm_helper.cpp
index e094313..a4b2fde 100644 (file)
--- a/src/amd/common/ac_llvm_helper.cpp
+++ b/src/amd/common/ac_llvm_helper.cpp
@@ -171,3 +171,10 @@ void ac_llvm_add_barrier_noop_pass(LLVMPassManagerRef passmgr)
 {
        llvm::unwrap(passmgr)->add(llvm::createBarrierNoopPass());
 }
+
+void ac_enable_global_isel(LLVMTargetMachineRef tm)
+{
+#if HAVE_LLVM >= 0x0700
+  reinterpret_cast<llvm::TargetMachine*>(tm)->setGlobalISel(true);
+#endif
+}

diff --git a/src/amd/common/ac_llvm_util.c b/src/amd/common/ac_llvm_util.c
index 0c8dbf1..678bc34 100644 (file)
--- a/src/amd/common/ac_llvm_util.c
+++ b/src/amd/common/ac_llvm_util.c
@@ -34,6 +34,7 @@
 #include <llvm-c/Transforms/Utils.h>
 #endif
 #include "c11/threads.h"
+#include "gallivm/lp_bld_misc.h"
 #include "util/u_math.h"
 
 #include <assert.h>
@@ -55,9 +56,13 @@ static void ac_init_llvm_target()
         * https://reviews.llvm.org/D26348
         *
         * "mesa" is the prefix for error messages.
+        *
+        * -global-isel-abort=2 is a no-op unless global isel has been enabled.
+        * This option tells the backend to fall-back to SelectionDAG and print
+        * a diagnostic message if global isel fails.
         */
-       const char *argv[2] = { "mesa", "-simplifycfg-sink-common=false" };
-       LLVMParseCommandLineOptions(2, argv, NULL);
+       const char *argv[3] = { "mesa", "-simplifycfg-sink-common=false", "-global-isel-abort=2" };
+       LLVMParseCommandLineOptions(3, argv, NULL);
 }
 
 static once_flag ac_init_llvm_target_once_flag = ONCE_FLAG_INIT;
@@ -164,6 +169,8 @@ static LLVMTargetMachineRef ac_create_target_machine(enum radeon_family family,
 
        if (out_triple)
                *out_triple = triple;
+       if (tm_options & AC_TM_ENABLE_GLOBAL_ISEL)
+               ac_enable_global_isel(tm);
        return tm;
 }
 

diff --git a/src/amd/common/ac_llvm_util.h b/src/amd/common/ac_llvm_util.h
index e5b9303..d4dea4d 100644 (file)
--- a/src/amd/common/ac_llvm_util.h
+++ b/src/amd/common/ac_llvm_util.h
@@ -63,6 +63,7 @@ enum ac_target_machine_options {
        AC_TM_FORCE_DISABLE_XNACK = (1 << 3),
        AC_TM_PROMOTE_ALLOCA_TO_SCRATCH = (1 << 4),
        AC_TM_CHECK_IR = (1 << 5),
+       AC_TM_ENABLE_GLOBAL_ISEL = (1 << 6),
 };
 
 enum ac_float_mode {
@@ -134,6 +135,7 @@ void ac_destroy_llvm_passes(struct ac_compiler_passes *p);
 bool ac_compile_module_to_binary(struct ac_compiler_passes *p, LLVMModuleRef module,
                                 struct ac_shader_binary *binary);
 void ac_llvm_add_barrier_noop_pass(LLVMPassManagerRef passmgr);
+void ac_enable_global_isel(LLVMTargetMachineRef tm);
 
 #ifdef __cplusplus
 }

diff --git a/src/gallium/drivers/radeonsi/si_pipe.c b/src/gallium/drivers/radeonsi/si_pipe.c
index d3d0c0e..9823ddb 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_pipe.c
+++ b/src/gallium/drivers/radeonsi/si_pipe.c
@@ -57,6 +57,7 @@ static const struct debug_named_value debug_options[] = {
        /* Shader compiler options the shader cache should be aware of: */
        { "unsafemath", DBG(UNSAFE_MATH), "Enable unsafe math shader optimizations" },
        { "sisched", DBG(SI_SCHED), "Enable LLVM SI Machine Instruction Scheduler." },
+       { "gisel", DBG(GISEL), "Enable LLVM global instruction selector." },
 
        /* Shader compiler options (with no effect on the shader cache): */
        { "checkir", DBG(CHECK_IR), "Enable additional sanity checks on shader IR" },
@@ -109,6 +110,7 @@ static void si_init_compiler(struct si_screen *sscreen,
 {
        enum ac_target_machine_options tm_options =
                (sscreen->debug_flags & DBG(SI_SCHED) ? AC_TM_SISCHED : 0) |
+               (sscreen->debug_flags & DBG(GISEL) ? AC_TM_ENABLE_GLOBAL_ISEL : 0) |
                (sscreen->info.chip_class >= GFX9 ? AC_TM_FORCE_ENABLE_XNACK : 0) |
                (sscreen->info.chip_class < GFX9 ? AC_TM_FORCE_DISABLE_XNACK : 0) |
                (!sscreen->llvm_has_working_vgpr_indexing ? AC_TM_PROMOTE_ALLOCA_TO_SCRATCH : 0) |
@@ -756,6 +758,7 @@ static void si_disk_cache_create(struct si_screen *sscreen)
                        /* These flags affect shader compilation. */
                        #define ALL_FLAGS (DBG(FS_CORRECT_DERIVS_AFTER_KILL) | \
                                           DBG(SI_SCHED) | \
+                                          DBG(GISEL) | \
                                           DBG(UNSAFE_MATH) | \
                                           DBG(NIR))
                        uint64_t shader_debug_flags = sscreen->debug_flags &

diff --git a/src/gallium/drivers/radeonsi/si_pipe.h b/src/gallium/drivers/radeonsi/si_pipe.h
index 301c168..4a3e8bb 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_pipe.h
+++ b/src/gallium/drivers/radeonsi/si_pipe.h
@@ -121,6 +121,7 @@ enum {
        DBG_FS_CORRECT_DERIVS_AFTER_KILL,
        DBG_UNSAFE_MATH,
        DBG_SI_SCHED,
+       DBG_GISEL,
 
        /* Shader compiler options (with no effect on the shader cache): */
        DBG_CHECK_IR,