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authorJosé Fonseca <jfonseca@vmware.com>2010-07-22 18:37:46 +0100
committerJosé Fonseca <jfonseca@vmware.com>2010-07-29 19:10:59 +0100
commite3d2ebac115f7b7899664fefc2652fb829acfa27 (patch)
tree135cfc368ae426c6c6a485cb4a544098d636fedb /src
parent38f5b1bc38fde041162e90e0ba3955ac661e1abf (diff)
llvmpipe: Avoid corrupting the FPU stack with MMX instructions on 32bit OSes.
Unfortunately LLVM doesn't emit EMMS itself, and there is no easy/effective way to disable MMX. http://llvm.org/bugs/show_bug.cgi?id=3287
Diffstat (limited to 'src')
-rw-r--r--src/gallium/auxiliary/gallivm/lp_bld_misc.cpp24
-rw-r--r--src/gallium/drivers/llvmpipe/lp_state_fs.c5
2 files changed, 29 insertions, 0 deletions
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
index 5a9488b5f7..072408b268 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
+++ b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
@@ -39,6 +39,7 @@
#include <llvm/Target/TargetOptions.h>
#include <llvm/ExecutionEngine/ExecutionEngine.h>
#include <llvm/ExecutionEngine/JITEventListener.h>
+#include <llvm/Support/CommandLine.h>
#include "pipe/p_config.h"
#include "util/u_debug.h"
@@ -141,4 +142,27 @@ lp_set_target_options(void)
#if 0
llvm::UnsafeFPMath = true;
#endif
+
+#if 0
+ /*
+ * LLVM will generate MMX instructions for vectors <= 64 bits, leading to
+ * innefficient code, and in 32bit systems, to the corruption of the FPU
+ * stack given that it expects the user to generate the EMMS instructions.
+ *
+ * See also:
+ * - http://llvm.org/bugs/show_bug.cgi?id=3287
+ * - http://l4.me.uk/post/2009/06/07/llvm-wrinkle-3-configuration-what-configuration/
+ *
+ * XXX: Unfortunately this is not working.
+ */
+ static boolean first = FALSE;
+ if (first) {
+ static const char* options[] = {
+ "prog",
+ "-disable-mmx"
+ };
+ llvm::cl::ParseCommandLineOptions(2, const_cast<char**>(options));
+ first = FALSE;
+ }
+#endif
}
diff --git a/src/gallium/drivers/llvmpipe/lp_state_fs.c b/src/gallium/drivers/llvmpipe/lp_state_fs.c
index 5953d690a4..dbcc286417 100644
--- a/src/gallium/drivers/llvmpipe/lp_state_fs.c
+++ b/src/gallium/drivers/llvmpipe/lp_state_fs.c
@@ -676,6 +676,11 @@ generate_fragment(struct llvmpipe_context *lp,
color_ptr);
}
+#ifdef PIPE_ARCH_X86
+ /* Avoid corrupting the FPU stack on 32bit OSes. */
+ lp_build_intrinsic(builder, "llvm.x86.mmx.emms", LLVMVoidType(), NULL, 0);
+#endif
+
LLVMBuildRetVoid(builder);
LLVMDisposeBuilder(builder);