Large programs, e.g. gnome-shell and firefox, may tax the
addressability of the Medium code model once a (potentially unbounded)
number of dynamically generated JIT-compiled shader programs are
linked in and relocated. Yet the default code model as of LLVM 8 is
Medium or even Small.
The cost of changing from Medium to Large is negligible:
- an additional 8-byte pointer stored immediately before the shader entrypoint;
- change an add-immediate (addis) instruction to a load (ld).
Testing with WebGL Conformance
(https://www.khronos.org/registry/webgl/sdk/tests/webgl-conformance-tests.html)
yields clean runs with this change (and crashes without it).
Testing with glxgears shows no detectable performance difference.
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=
1753327,
1753789,
1543572,
1747110, and
1582226
Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/223
Co-authored by: Nemanja Ivanovic <nemanjai@ca.ibm.com>, Tom Stellard <tstellar@redhat.com>
CC: mesa-stable@lists.freedesktop.org
Signed-off-by: Ben Crocker <bcrocker@redhat.com>
(cherry picked from commit
9c3be6d21fa6a45852045d0286b80fb420f82fe3)
Conflicts resolved Dylan (PIPE_ARCH -> UTIL_ARCH rename)
* 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)
+
+#ifdef PIPE_ARCH_PPC_64
+ /*
+ * Large programs, e.g. gnome-shell and firefox, may tax the addressability
+ * of the Medium code model once dynamically generated JIT-compiled shader
+ * programs are linked in and relocated. Yet the default code model as of
+ * LLVM 8 is Medium or even Small.
+ * The cost of changing from Medium to Large is negligible:
+ * - an additional 8-byte pointer stored immediately before the shader entrypoint;
+ * - change an add-immediate (addis) instruction to a load (ld).
+ */
+ builder.setCodeModel(CodeModel::Large);
+
+#if PIPE_ARCH_LITTLE_ENDIAN
/*
* Versions of LLVM prior to 4.0 lacked a table entry for "POWER8NVL",
* resulting in (big-endian) "generic" being returned on
if (MCPU == "generic")
MCPU = "pwr8";
#endif
+#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());