gallivm: work around LLVM 2.6 bug when calling C functions

Create a constant int pointer to the C function, then cast it to the
function's type.  This avoids using trampoline code which seem to be
inadvertantly freed by LLVM in some situations (which leads to segfaults).
The root issue and work-around were found by José.

NOTE: This is a candidate for the 7.10 branch

2 files changed, 61 insertions, 11 deletions

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_const.h b/src/gallium/auxiliary/gallivm/lp_bld_const.h
index c749a7a315..680211fbbd 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_const.h
+++ b/src/gallium/auxiliary/gallivm/lp_bld_const.h
@@ -125,4 +125,22 @@ lp_build_const_float(struct gallivm_state *gallivm, float x)
 }
 
 
+/** Return constant-valued pointer to int */
+static INLINE LLVMValueRef
+lp_build_const_int_pointer(struct gallivm_state *gallivm, const void *ptr)
+{
+   LLVMTypeRef int_type;
+   LLVMValueRef v;
+
+   /* int type large enough to hold a pointer */
+   int_type = LLVMIntTypeInContext(gallivm->context, 8 * sizeof(void *));
+   v = LLVMConstInt(int_type, (unsigned long long) ptr, 0);
+   v = LLVMBuildIntToPtr(gallivm->builder, v,
+                         LLVMPointerType(int_type, 0),
+                         "cast int to ptr");
+   return v;
+}
+
+
+
 #endif /* !LP_BLD_CONST_H */
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_format_aos.c b/src/gallium/auxiliary/gallivm/lp_bld_format_aos.c
index 75d2e666f0..905cf66137 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_format_aos.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_format_aos.c
@@ -36,6 +36,7 @@
 #include "util/u_format.h"
 #include "util/u_memory.h"
 #include "util/u_math.h"
+#include "util/u_pointer.h"
 #include "util/u_string.h"
 
 #include "lp_bld_arit.h"
@@ -520,6 +521,7 @@ lp_build_fetch_rgba_aos(struct gallivm_state *gallivm,
       LLVMValueRef tmp_ptr;
       LLVMValueRef tmp;
       LLVMValueRef res;
+      LLVMValueRef callee;
       unsigned k;
 
       util_snprintf(name, sizeof name, "util_format_%s_fetch_rgba_8unorm",
@@ -535,6 +537,10 @@ lp_build_fetch_rgba_aos(struct gallivm_state *gallivm,
 
       function = LLVMGetNamedFunction(module, name);
       if (!function) {
+         /*
+          * Function to call looks like:
+          *   fetch(uint8_t *dst, const uint8_t *src, unsigned i, unsigned j)
+          */
          LLVMTypeRef ret_type;
          LLVMTypeRef arg_types[4];
          LLVMTypeRef function_type;
@@ -542,19 +548,26 @@ lp_build_fetch_rgba_aos(struct gallivm_state *gallivm,
          ret_type = LLVMVoidTypeInContext(gallivm->context);
          arg_types[0] = pi8t;
          arg_types[1] = pi8t;
-         arg_types[3] = arg_types[2] = LLVMIntTypeInContext(gallivm->context, sizeof(unsigned) * 8);
-         function_type = LLVMFunctionType(ret_type, arg_types, Elements(arg_types), 0);
+         arg_types[2] = i32t;
+         arg_types[3] = i32t;
+         function_type = LLVMFunctionType(ret_type, arg_types,
+                                          Elements(arg_types), 0);
          function = LLVMAddFunction(module, name, function_type);
 
          LLVMSetFunctionCallConv(function, LLVMCCallConv);
          LLVMSetLinkage(function, LLVMExternalLinkage);
 
          assert(LLVMIsDeclaration(function));
-
-         LLVMAddGlobalMapping(gallivm->engine, function,
-                              func_to_pointer((func_pointer)format_desc->fetch_rgba_8unorm));
       }
 
+      /* make const pointer for the C fetch_rgba_float function */
+      callee = lp_build_const_int_pointer(gallivm,
+         func_to_pointer((func_pointer) format_desc->fetch_rgba_float));
+
+      /* cast the callee pointer to the function's type */
+      function = LLVMBuildBitCast(builder, callee,
+                                  LLVMTypeOf(function), "cast callee");
+
       tmp_ptr = lp_build_alloca(gallivm, i32t, "");
 
       res = LLVMGetUndef(LLVMVectorType(i32t, num_pixels));
@@ -619,10 +632,13 @@ lp_build_fetch_rgba_aos(struct gallivm_state *gallivm,
       LLVMTypeRef f32t = LLVMFloatTypeInContext(gallivm->context);
       LLVMTypeRef f32x4t = LLVMVectorType(f32t, 4);
       LLVMTypeRef pf32t = LLVMPointerType(f32t, 0);
+      LLVMTypeRef pi8t = LLVMPointerType(LLVMInt8TypeInContext(gallivm->context), 0);
+      LLVMTypeRef i32t = LLVMInt32TypeInContext(gallivm->context);
       LLVMValueRef function;
       LLVMValueRef tmp_ptr;
       LLVMValueRef tmps[LP_MAX_VECTOR_LENGTH/4];
       LLVMValueRef res;
+      LLVMValueRef callee;
       unsigned k;
 
       util_snprintf(name, sizeof name, "util_format_%s_fetch_rgba_float",
@@ -638,26 +654,42 @@ lp_build_fetch_rgba_aos(struct gallivm_state *gallivm,
 
       function = LLVMGetNamedFunction(module, name);
       if (!function) {
+         /*
+          * Function to call looks like:
+          *   fetch(float *dst, const uint8_t *src, unsigned i, unsigned j)
+          */
          LLVMTypeRef ret_type;
          LLVMTypeRef arg_types[4];
          LLVMTypeRef function_type;
 
          ret_type = LLVMVoidTypeInContext(gallivm->context);
          arg_types[0] = pf32t;
-         arg_types[1] = LLVMPointerType(LLVMInt8TypeInContext(gallivm->context), 0);
-         arg_types[3] = arg_types[2] = LLVMIntTypeInContext(gallivm->context, sizeof(unsigned) * 8);
-         function_type = LLVMFunctionType(ret_type, arg_types, Elements(arg_types), 0);
+         arg_types[1] = pi8t;
+         arg_types[2] = i32t;
+         arg_types[3] = i32t;
+         function_type = LLVMFunctionType(ret_type, arg_types,
+                                          Elements(arg_types), 0);
          function = LLVMAddFunction(module, name, function_type);
 
          LLVMSetFunctionCallConv(function, LLVMCCallConv);
          LLVMSetLinkage(function, LLVMExternalLinkage);
 
          assert(LLVMIsDeclaration(function));
-
-         LLVMAddGlobalMapping(gallivm->engine, function,
-                              func_to_pointer((func_pointer)format_desc->fetch_rgba_float));
       }
 
+      /* Note: we're using this casting here instead of LLVMAddGlobalMapping()
+       * to work around a bug in LLVM 2.6.
+       */
+
+      /* make const pointer for the C fetch_rgba_float function */
+      callee = lp_build_const_int_pointer(gallivm,
+         func_to_pointer((func_pointer) format_desc->fetch_rgba_float));
+
+      /* cast the callee pointer to the function's type */
+      function = LLVMBuildBitCast(builder, callee,
+                                  LLVMTypeOf(function), "cast callee");
+
+
       tmp_ptr = lp_build_alloca(gallivm, f32x4t, "");
 
       /*