[Mesa-dev] [PATCH 05/12] gallivm: Use LLVM global context.

[jfonseca at vmware.com]

From: José Fonseca <jfonseca at vmware.com>

I saw that LLVM internally uses its global context for some things, even
when we use our own.  Given ours is also global, might as well use
LLVM's.

However, sepearate contexts can still be enabled with a simple source
code modification, for when the need/benefit arises.
---
 src/gallium/auxiliary/gallivm/lp_bld_init.c | 40 ++++++++++++-----------------
 1 file changed, 17 insertions(+), 23 deletions(-)

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_init.c b/src/gallium/auxiliary/gallivm/lp_bld_init.c
index 6934a28..2d854e9 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_init.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_init.c
@@ -68,6 +68,16 @@
 void LLVMLinkInMCJIT();
 #endif
 
+/*
+ * LLVM has several global caches which pointing/derived from objects
+ * owned by the context, so if we freeing contexts causes
+ * memory leaks and false cache hits when these objects are destroyed.
+ *
+ * TODO: For thread safety on multi-threaded OpenGL we should use one LLVM
+ * context per thread, and put them in a pool when threads are destroyed.
+ */
+#define USE_GLOBAL_CONTEXT 1
+
 
 #ifdef DEBUG
 unsigned gallivm_debug = 0;
@@ -196,16 +206,12 @@ free_gallivm_state(struct gallivm_state *gallivm)
    }
 #endif
 
-   /* Never free the LLVM context.
-    */
-#if 0
-   if (gallivm->context)
-      LLVMContextDispose(gallivm->context);
-#endif
-
    if (gallivm->builder)
       LLVMDisposeBuilder(gallivm->builder);
 
+   if (!USE_GLOBAL_CONTEXT && gallivm->context)
+      LLVMContextDispose(gallivm->context);
+
    gallivm->engine = NULL;
    gallivm->target = NULL;
    gallivm->module = NULL;
@@ -277,19 +283,6 @@ fail:
 
 
 /**
- * Singleton
- *
- * We must never free LLVM contexts, because LLVM has several global caches
- * which pointing/derived from objects owned by the context, causing false
- * memory leaks and false cache hits when these objects are destroyed.
- *
- * TODO: For thread safety on multi-threaded OpenGL we should use one LLVM
- * context per thread, and put them in a pool when threads are destroyed.
- */
-static LLVMContextRef gallivm_context = NULL;
-
-
-/**
  * Allocate gallivm LLVM objects.
  * \return  TRUE for success, FALSE for failure
  */
@@ -301,10 +294,11 @@ init_gallivm_state(struct gallivm_state *gallivm)
 
    lp_build_init();
 
-   if (!gallivm_context) {
-      gallivm_context = LLVMContextCreate();
+   if (USE_GLOBAL_CONTEXT) {
+      gallivm->context = LLVMGetGlobalContext();
+   } else {
+      gallivm->context = LLVMContextCreate();
    }
-   gallivm->context = gallivm_context;
    if (!gallivm->context)
       goto fail;
 
-- 
1.9.1