36 lines
1.4 KiB
Diff
36 lines
1.4 KiB
Diff
From ca11b53896365c948426974cb90e8f71c70d123b Mon Sep 17 00:00:00 2001
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From: Simon South <simon@simonsouth.net>
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Date: Sun, 31 May 2020 20:36:43 -0400
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Subject: [PATCH] Guard floating-point opcodes with explicit memory barrier
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---
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src/interp/engine/interp-inlining.h | 11 ++++++++++-
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1 file changed, 10 insertions(+), 1 deletion(-)
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diff --git a/src/interp/engine/interp-inlining.h b/src/interp/engine/interp-inlining.h
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index 3339b0e..4ee5c5a 100644
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--- jamvm/jamvm/src/interp/engine/interp-inlining.h
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+++ jamvm/jamvm/src/interp/engine/interp-inlining.h
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@@ -78,8 +78,17 @@
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4.3, we need to insert a label, and ensure its address
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is taken (to stop it being optimised out). However,
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this reduces performance on PowerPC by approx 1 - 2%.
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+
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+ With gcc 5 and newer an asm statement with a "memory"
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+ clobber argument explicitly sets a memory barrier for the
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+ compiler, preventing it from reordering memory accesses
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+ in a way that breaks decaching.
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*/
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-#if (__GNUC__ == 4) && (__GNUC_MINOR__ >= 3)
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+#if (__GNUC__ > 4)
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+#define DEF_GUARD_TABLE(level) /* none */
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+#define GUARD(opcode, level) __asm__("" ::: "memory");
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+#define GUARD_TBLS /* none */
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+#elif (__GNUC__ == 4) && (__GNUC_MINOR__ >= 3)
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#define DEF_GUARD_TABLE(level) DEF_HANDLER_TABLE(level, GUARD)
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#define GUARD(opcode, level) label(opcode, level, GUARD)
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#define GUARD_TBLS , HNDLR_TBLS(GUARD)
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--
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2.26.2
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