Attachment 106092 Details for Bug 83735 – [PATCH 2/2] gallivm: set mcpu when initializing llvm execution engine

[patch] [PATCH 2/2] gallivm: set mcpu when initializing llvm execution engine

0002-gallivm-set-mcpu-when-initializing-llvm-execution-en.patch (text/plain), 3.28 KB, created by Evangelos Foutras on 2014-09-10 22:43:20 UTC

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Creator: Evangelos Foutras

Created: 2014-09-10 22:43:20 UTC

Size: 3.28 KB

patch

obsolete

>From ebe30fd4d4a90219431b6947f233473b2cf518a5 Mon Sep 17 00:00:00 2001
>From: Roland Scheidegger <sroland@vmware.com>
>Date: Thu, 19 Jun 2014 03:27:26 +0200
>Subject: [PATCH 2/2] gallivm: set mcpu when initializing llvm execution engine
>
>Previously llvm detected cpu features automatically when the execution engine
>was created (based on host cpu). This is no longer the case, which meant llvm
>was then not able to emit some of the intrinsics we used as we didn't specify
>any sse attributes (only on avx supporting systems this was not a problem since
>despite at least some llvm versions enabling it anyway we always set this
>manually). So, instead of trying to figure out which MAttrs to set just set
>MCPU.
>
>This fixes https://bugs.freedesktop.org/show_bug.cgi?id=77493.
>
>Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
>Tested-by: Vinson Lee <vlee@freedesktop.org>
>(cherry picked from commit cad60420d5ea36a4b6fa2e6c91317f71423aa63e)
>---
> src/gallium/auxiliary/gallivm/lp_bld_misc.cpp | 24 ++++++++++++++++++++++--
> 1 file changed, 22 insertions(+), 2 deletions(-)
>
>diff --git a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
>index 45c985d..395ac7b 100644
>--- a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
>+++ b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
>@@ -59,6 +59,7 @@
> #include <llvm/ExecutionEngine/JITMemoryManager.h>
> #endif
> #include <llvm/Support/CommandLine.h>
>+#include <llvm/Support/Host.h>
> #include <llvm/Support/PrettyStackTrace.h>
> 
> #if HAVE_LLVM >= 0x0300
>@@ -309,8 +310,8 @@ lp_build_create_jit_compiler_for_module(LLVMExecutionEngineRef *OutJIT,
>       /*
>        * AVX feature is not automatically detected from CPUID by the X86 target
>        * yet, because the old (yet default) JIT engine is not capable of
>-       * emitting the opcodes.  But as we're using MCJIT here, it is safe to
>-       * add set this attribute.
>+       * emitting the opcodes. On newer llvm versions it is and at least some
>+       * versions (tested with 3.3) will emit avx opcodes without this anyway.
>        */
>       MAttrs.push_back("+avx");
>       if (util_cpu_caps.has_f16c) {
>@@ -318,9 +319,28 @@ lp_build_create_jit_compiler_for_module(LLVMExecutionEngineRef *OutJIT,
>       }
>       builder.setMAttrs(MAttrs);
>    }
>+
>+#if HAVE_LLVM >= 0x0305
>+   StringRef MCPU = llvm::sys::getHostCPUName();
>+   /*
>+    * The cpu bits are no longer set automatically, so need to set mcpu manually.
>+    * Note that the MAttrs set above will be sort of ignored (since we should
>+    * not set any which would not be set by specifying the cpu anyway).
>+    * It ought to be safe though since getHostCPUName() should include bits
>+    * not only from the cpu but environment as well (for instance if it's safe
>+    * to use avx instructions which need OS support). According to
>+    * http://llvm.org/bugs/show_bug.cgi?id=19429 however if I understand this
>+    * right it may be necessary to specify older cpu (or disable mattrs) though
>+    * when not using MCJIT so no instructions are generated which the old JIT
>+    * can't handle. Not entirely sure if we really need to do anything yet.
>+    */
>+   builder.setMCPU(MCPU);
>+#endif
>+
>    builder.setJITMemoryManager(JITMemoryManager::CreateDefaultMemManager());
> 
>    ExecutionEngine *JIT;
>+
> #if HAVE_LLVM >= 0x0302
>    JIT = builder.create();
> #else
>-- 
>2.1.0
>

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