From 41b88f47089196292aacac48e32c90da22aa34af Mon Sep 17 00:00:00 2001
From: Julian Seward <jseward@acm.org>
Date: Mon, 8 Aug 2005 00:33:37 +0000
Subject: [PATCH] Don't emit cmovl since older x86s don't support it; instead
 emit a conditional jump over an unconditional move.

git-svn-id: svn://svn.valgrind.org/vex/trunk@1321
---
 VEX/priv/host-x86/hdefs.c | 33 +++++++++++++++++++++++++++++++++
 VEX/pub/libvex.h          |  2 +-
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/VEX/priv/host-x86/hdefs.c b/VEX/priv/host-x86/hdefs.c
index d0fccf1774..952cc75be2 100644
--- a/VEX/priv/host-x86/hdefs.c
+++ b/VEX/priv/host-x86/hdefs.c
@@ -2204,7 +2204,9 @@ Int emit_X86Instr ( UChar* buf, Int nbuf, X86Instr* i )
 
    case Xin_CMov32:
       vassert(i->Xin.CMov32.cond != Xcc_ALWAYS);
+
       /* This generates cmov, which is illegal on P54/P55. */
+      /*
       *p++ = 0x0F;
       *p++ = toUChar(0x40 + (0xF & i->Xin.CMov32.cond));
       if (i->Xin.CMov32.src->tag == Xrm_Reg) {
@@ -2215,6 +2217,37 @@ Int emit_X86Instr ( UChar* buf, Int nbuf, X86Instr* i )
          p = doAMode_M(p, i->Xin.CMov32.dst, i->Xin.CMov32.src->Xrm.Mem.am);
          goto done;
       }
+      */
+
+      /* Alternative version which works on any x86 variant. */
+      /* jmp fwds if !condition */
+      *p++ = 0x70 + (i->Xin.CMov32.cond ^ 1);
+      *p++ = 0; /* # of bytes in the next bit, which we don't know yet */
+      ptmp = p;
+
+      switch (i->Xin.CMov32.src->tag) {
+         case Xrm_Reg:
+            /* Big sigh.  This is movl E -> G ... */
+            *p++ = 0x89;
+            p = doAMode_R(p, i->Xin.CMov32.src->Xrm.Reg.reg,
+                             i->Xin.CMov32.dst);
+
+            break;
+         case Xrm_Mem:
+            /* ... whereas this is movl G -> E.  That's why the args
+               to doAMode_R appear to be the wrong way round in the
+               Xrm_Reg case. */
+            *p++ = 0x8B;
+            p = doAMode_M(p, i->Xin.CMov32.dst,
+                             i->Xin.CMov32.src->Xrm.Mem.am);
+            break;
+         default:
+            goto bad;
+      }
+      /* Fill in the jump offset. */
+      *(ptmp-1) = p - ptmp;
+      goto done;
+
       break;
 
    case Xin_LoadEX:
diff --git a/VEX/pub/libvex.h b/VEX/pub/libvex.h
index 97cb8aa9dc..8bf068e5ae 100644
--- a/VEX/pub/libvex.h
+++ b/VEX/pub/libvex.h
@@ -74,7 +74,7 @@ typedef
    enum {
       VexSubArch_INVALID,
       VexSubArch_NONE,        /* Arch has no variants */
-      VexSubArchX86_sse0,     /* has SSE state but no insns (Pentium II) */
+      VexSubArchX86_sse0,     /* no SSE state; or SSE state but no insns */
       VexSubArchX86_sse1,     /* SSE1 support (Pentium III) */
       VexSubArchX86_sse2,     /* SSE2 support (Pentium 4) */
       VexSubArchARM_v4,       /* ARM version 4 */
-- 
2.47.3