From 9aca538a8ae017222aded41bc530fef150db351c Mon Sep 17 00:00:00 2001

From: Tom Stellard <tstellar@redhat.com>

Date: Fri, 5 May 2017 01:07:00 +0000

Subject: [PATCH] gallivm: Make sure module has the correct data layout when

 pass manager runs

The datalayout for modules was purposely not being set in order to work around

the fact that the ExecutionEngine requires that the module's datalayout

matches the datalayout of the TargetMachine that the ExecutionEngine is

using.

When the pass manager runs on a module with no datalayout, it uses

the default datalayout which is little-endian.  This causes problems

on big-endian targets, because some optimizations that are legal on

little-endian or illegal on big-endian.

To resolve this, we set the datalayout prior to running the pass

manager, and then clear it before creating the ExectionEngine.

This patch fixes a lot of piglit tests on big-endian ppc64.

Cc: mesa-stable@lists.freedesktop.org

---

 src/gallium/auxiliary/gallivm/lp_bld_init.c | 34 +++++++++++++++--------------

 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_init.c b/src/gallium/auxiliary/gallivm/lp_bld_init.c

index ef2580e..9f1ade6 100644

--- a/src/gallium/auxiliary/gallivm/lp_bld_init.c

+++ b/src/gallium/auxiliary/gallivm/lp_bld_init.c

@@ -125,19 +125,6 @@ create_pass_manager(struct gallivm_state *gallivm)

    LLVMAddTargetData(gallivm->target, gallivm->passmgr);

 #endif

-   /* 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.

@@ -145,9 +132,6 @@ create_pass_manager(struct gallivm_state *gallivm)

       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,

@@ -628,6 +612,24 @@ gallivm_compile_module(struct gallivm_state *gallivm)

    }

    if (use_mcjit) {

+      /* 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.

+       *

+       * We must make sure we do this after running the optimization passes,

+       * because those passes need a correct datalayout string.  For example,

+       * if those optimization passes see an empty datalayout, they will assume

+       * this is a little endian target and will do optimizations that break big

+       * endian machines.

+       *

+       * 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()

+       */

+      LLVMSetDataLayout(gallivm->module, "");

       assert(!gallivm->engine);

       if (!init_gallivm_engine(gallivm)) {

          assert(0);

-- 

2.9.3