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[PULL,01/18] tcg/i386: Use byte form of xgetbv instruction

Message ID 20180614193147.29680-2-richard.henderson@linaro.org
State Superseded
Headers show
Series tcg queued patches | expand

Commit Message

Richard Henderson June 14, 2018, 7:31 p.m. UTC 
From: John Arbuckle <programmingkidx@gmail.com>


The assembler in most versions of Mac OS X is pretty old and does not
support the xgetbv instruction.  To go around this problem, the raw
encoding of the instruction is used instead.

Signed-off-by: John Arbuckle <programmingkidx@gmail.com>

Message-Id: <20180604215102.11002-1-programmingkidx@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 tcg/i386/tcg-target.inc.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

-- 
2.17.1
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Patch

diff --git a/tcg/i386/tcg-target.inc.c b/tcg/i386/tcg-target.inc.c
index 5357909fff..0d0ff524b7 100644
--- a/tcg/i386/tcg-target.inc.c
+++ b/tcg/i386/tcg-target.inc.c
@@ -3501,7 +3501,10 @@  static void tcg_target_init(TCGContext *s)
            sure of not hitting invalid opcode.  */
         if (c & bit_OSXSAVE) {
             unsigned xcrl, xcrh;
-            asm ("xgetbv" : "=a" (xcrl), "=d" (xcrh) : "c" (0));
+            /* The xgetbv instruction is not available to older versions of
+             * the assembler, so we encode the instruction manually.
+             */
+            asm(".byte 0x0f, 0x01, 0xd0" : "=a" (xcrl), "=d" (xcrh) : "c" (0));
             if ((xcrl & 6) == 6) {
                 have_avx1 = (c & bit_AVX) != 0;
                 have_avx2 = (b7 & bit_AVX2) != 0;