gallivm: Setup a global optimization pass.

Modules are still free to setup their own optimization passes, but for the
normal case it should not be necessary.

src/gallium/auxiliary/gallivm/lp_bld_init.c

@@ -32,6 +32,8 @@
 #include "lp_bld_debug.h"
 #include "lp_bld_init.h"
 
+#include <llvm-c/Transforms/Scalar.h>
+
 
 #ifdef DEBUG
 unsigned gallivm_debug = 0;
@@ -50,6 +52,7 @@ LLVMModuleRef lp_build_module = NULL;
 LLVMExecutionEngineRef lp_build_engine = NULL;
 LLVMModuleProviderRef lp_build_provider = NULL;
 LLVMTargetDataRef lp_build_target = NULL;
+LLVMPassManagerRef lp_build_pass = NULL;
 
 
 /*
@@ -127,6 +130,33 @@ lp_build_init(void)
    if (!lp_build_target)
       lp_build_target = LLVMGetExecutionEngineTargetData(lp_build_engine);
 
+   if (!lp_build_pass) {
+      lp_build_pass = LLVMCreateFunctionPassManager(lp_build_provider);
+      LLVMAddTargetData(lp_build_target, lp_build_pass);
+
+      if ((gallivm_debug & GALLIVM_DEBUG_NO_OPT) == 0) {
+         /* These are the passes currently listed in llvm-c/Transforms/Scalar.h,
+          * but there are more on SVN. */
+         /* TODO: Add more passes */
+         LLVMAddCFGSimplificationPass(lp_build_pass);
+         LLVMAddPromoteMemoryToRegisterPass(lp_build_pass);
+         LLVMAddConstantPropagationPass(lp_build_pass);
+         if(util_cpu_caps.has_sse4_1) {
+            /* FIXME: There is a bug in this pass, whereby the combination of fptosi
+             * and sitofp (necessary for trunc/floor/ceil/round implementation)
+             * somehow becomes invalid code.
+             */
+            LLVMAddInstructionCombiningPass(lp_build_pass);
+         }
+         LLVMAddGVNPass(lp_build_pass);
+      } else {
+         /* We need at least this pass to prevent the backends to fail in
+          * unexpected ways.
+          */
+         LLVMAddPromoteMemoryToRegisterPass(lp_build_pass);
+      }
+   }
+
    util_cpu_detect();
 
 #if 0

src/gallium/auxiliary/gallivm/lp_bld_init.h

@@ -38,6 +38,7 @@ extern LLVMModuleRef lp_build_module;
 extern LLVMExecutionEngineRef lp_build_engine;
 extern LLVMModuleProviderRef lp_build_provider;
 extern LLVMTargetDataRef lp_build_target;
+extern LLVMPassManagerRef lp_build_pass;
 
 
 void