From b934aae36410e09892e772b26f61fed5d037fc69 Mon Sep 17 00:00:00 2001 From: Ben Crocker Date: Fri, 10 Feb 2017 18:08:07 -0500 Subject: [PATCH] gallivm: Override getHostCPUName() "generic" w/ "pwr8" (v4) If llvm::sys::getHostCPUName() returns "generic", override it with "pwr8" (on PPC64LE). This is a work-around for a bug in LLVM: a table entry for "POWER8NVL" is missing, resulting in (big-endian) "generic" being returned on little-endian Power8NVL systems. The result is that code that attempts to load the least significant 32 bits of a 64-bit quantity in memory loads the wrong half. This omission should be fixed in the next version of LLVM (4.0), but this work-around should be left in place in case some future version of POWER also ends up unrepresented in LLVM's table. This workaround fixes failures in the Piglit arb_gpu_shader_fp64 conversion tests on POWER8NVL processors. (V4: add similar comment in the code.) Signed-off-by: Ben Crocker Cc: 12.0 13.0 17.0 Acked-by: Emil Velikov --- src/gallium/auxiliary/gallivm/lp_bld_misc.cpp | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp index 4115f1e..6c64e4d 100644 --- a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp +++ b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp @@ -644,6 +644,19 @@ lp_build_create_jit_compiler_for_module(LLVMExecutionEngineRef *OutJIT, * 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. */ +#if defined(PIPE_ARCH_LITTLE_ENDIAN) && defined(PIPE_ARCH_PPC_64) + /* + * Versions of LLVM prior to 4.0 lacked a table entry for "POWER8NVL", + * resulting in (big-endian) "generic" being returned on + * little-endian Power8NVL systems. The result was that code that + * attempted to load the least significant 32 bits of a 64-bit quantity + * from memory loaded the wrong half. This resulted in failures in some + * Piglit tests, e.g. + * .../arb_gpu_shader_fp64/execution/conversion/frag-conversion-explicit-double-uint + */ + if (MCPU == "generic") + MCPU = "pwr8"; +#endif builder.setMCPU(MCPU); if (gallivm_debug & (GALLIVM_DEBUG_IR | GALLIVM_DEBUG_ASM | GALLIVM_DEBUG_DUMP_BC)) { debug_printf("llc -mcpu option: %s\n", MCPU.str().c_str()); -- 2.7.4