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From d0ff02e567541468309923fed2320da6cbd81779 Mon Sep 17 00:00:00 2001
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From: Ben Crocker <bcrocker@redhat.com>
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Date: Thu, 21 Nov 2019 17:33:31 -0500
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Subject: [PATCH] llvmpipe: use ppc64le/ppc64 Large code model for JIT-compiled
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shaders
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Large programs, e.g. gnome-shell and firefox, may tax the
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addressability of the Medium code model once a (potentially unbounded)
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number of dynamically generated JIT-compiled shader programs are
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linked in and relocated. Yet the default code model as of LLVM 8 is
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Medium or even Small.
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The cost of changing from Medium to Large is negligible:
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- an additional 8-byte pointer stored immediately before the shader entrypoint;
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- change an add-immediate (addis) instruction to a load (ld).
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Testing with WebGL Conformance
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(https://www.khronos.org/registry/webgl/sdk/tests/webgl-conformance-tests.html)
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yields clean runs with this change (and crashes without it).
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Testing with glxgears shows no detectable performance difference.
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1753327, 1543572, 1747110, and 1582226
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Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/223
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Co-authored by: Nemanja Ivanovic <nemanjai@ca.ibm.com>, Tom Stellard <tstellar@redhat.com>
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CC: mesa-stable@lists.freedesktop.org
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Signed-off-by: Ben Crocker <bcrocker@redhat.com>
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Reviewed-by: Adam Jackson <ajax@redhat.com>
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---
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src/gallium/auxiliary/gallivm/lp_bld_misc.cpp | 15 ++++++++++++++-
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1 file changed, 14 insertions(+), 1 deletion(-)
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diff --git a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
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--- a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
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+++ b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
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@@ -686,7 +686,19 @@ lp_build_create_jit_compiler_for_module(LLVMExecutionEngineRef *OutJIT,
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* when not using MCJIT so no instructions are generated which the old JIT
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* can't handle. Not entirely sure if we really need to do anything yet.
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*/
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-#if defined(PIPE_ARCH_LITTLE_ENDIAN) && defined(PIPE_ARCH_PPC_64)
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+#ifdef PIPE_ARCH_PPC_64
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+ /*
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+ * Large programs, e.g. gnome-shell and firefox, may tax the addressability
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+ * of the Medium code model once dynamically generated JIT-compiled shader
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+ * programs are linked in and relocated. Yet the default code model as of
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+ * LLVM 8 is Medium or even Small.
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+ * The cost of changing from Medium to Large is negligible:
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+ * - an additional 8-byte pointer stored immediately before the shader entrypoint;
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+ * - change an add-immediate (addis) instruction to a load (ld).
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+ */
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+ builder.setCodeModel(CodeModel::Large);
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+
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+#ifdef PIPE_ARCH_LITTLE_ENDIAN
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/*
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* Versions of LLVM prior to 4.0 lacked a table entry for "POWER8NVL",
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* resulting in (big-endian) "generic" being returned on
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@@ -698,6 +710,7 @@ lp_build_create_jit_compiler_for_module(LLVMExecutionEngineRef *OutJIT,
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*/
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if (MCPU == "generic")
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MCPU = "pwr8";
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+#endif
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#endif
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builder.setMCPU(MCPU);
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if (gallivm_debug & (GALLIVM_DEBUG_IR | GALLIVM_DEBUG_ASM | GALLIVM_DEBUG_DUMP_BC)) {
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--
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2.21.0
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