Mesa (master): gallivm: Initialize LLVM Modules' s DataLayout to an empty string.

[Tom Stellard]

Module: Mesa
Branch: master
Commit: 4be30fcd058209966fc72fbfa51bbe881c307ed5
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=4be30fcd058209966fc72fbfa51bbe881c307ed5

Author: Tom Stellard <thomas.stellard at amd.com>
Date:   Mon Jul 20 15:12:56 2015 +0000

gallivm: Initialize LLVM Modules's DataLayout to an empty string.

This fixes crashes in llvmpipe with LLVM 3.8 and also some piglit tests
on radeonsi that use the draw module.

This is just a temporary solution.  The correct solution will require
creating a TargetMachine during gallivm initialization and pulling the
DataLayout from there.  This will be a somewhat invasive change, and it
will need to be validatated on multiple LLVM versions.

https://llvm.org/bugs/show_bug.cgi?id=24172

Reviewed-by: Roland Scheidegger <sroland at vmware.com>

---

 src/gallium/auxiliary/gallivm/lp_bld_init.c |   28 ++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_init.c b/src/gallium/auxiliary/gallivm/lp_bld_init.c
index 384ea86..017d075 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_init.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_init.c
@@ -106,7 +106,6 @@ enum LLVM_CodeGenOpt_Level {
 static boolean
 create_pass_manager(struct gallivm_state *gallivm)
 {
-   char *td_str;
    assert(!gallivm->passmgr);
    assert(gallivm->target);
 
@@ -122,10 +121,29 @@ create_pass_manager(struct gallivm_state *gallivm)
    // Old versions of LLVM get the DataLayout from the pass manager.
    LLVMAddTargetData(gallivm->target, gallivm->passmgr);
 
-   // New ones from the Module.
-   td_str = LLVMCopyStringRepOfTargetData(gallivm->target);
-   LLVMSetDataLayout(gallivm->module, td_str);
-   free(td_str);
+   /* Setting the module's DataLayout to an empty string will cause the
+    * ExecutionEngine to copy to the DataLayout string from its target
+    * machine to the module.  As of LLVM 3.8 the module and the execution
+    * engine are required to have the same DataLayout.
+    *
+    * TODO: This is just a temporary work-around.  The correct solution is
+    * for gallivm_init_state() to create a TargetMachine and pull the
+    * DataLayout from there.  Currently, the TargetMachine used by llvmpipe
+    * is being implicitly created by the EngineBuilder in
+    * lp_build_create_jit_compiler_for_module()
+    */
+
+#if HAVE_LLVM < 0x0308
+   {
+      char *td_str;
+      // New ones from the Module.
+      td_str = LLVMCopyStringRepOfTargetData(gallivm->target);
+      LLVMSetDataLayout(gallivm->module, td_str);
+      free(td_str);
+   }
+#else
+   LLVMSetDataLayout(gallivm->module, "");
+#endif
 
    if ((gallivm_debug & GALLIVM_DEBUG_NO_OPT) == 0) {
       /* These are the passes currently listed in llvm-c/Transforms/Scalar.h,