From 463290b8eacd108ff524f853d2c5cf59a45210f6 Mon Sep 17 00:00:00 2001
From: Eric Caruso <zircean@fb.com>
Date: Fri, 21 Jun 2013 18:24:00 -0700
Subject: [PATCH] Adds decl and decw instructions that operate on registers

Cherry-pick of D851076 which was reverted in the OSS
segfault catastrophe.
---
 hphp/util/asm-x64.h    |  3 ++-
 hphp/util/test/asm.cpp | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/hphp/util/asm-x64.h b/hphp/util/asm-x64.h
index a307082398e..e2c083d700d 100644
--- a/hphp/util/asm-x64.h
+++ b/hphp/util/asm-x64.h
@@ -1090,7 +1090,8 @@ struct X64Assembler {
   void incl(Reg32 r)  { instrR(instr_inc,  r); }
   void incw(Reg16 r)  { instrR(instr_inc,  r); }
   void decq(Reg64 r)  { instrR(instr_dec,  r); }
-  // decl(Reg32) cannot be encoded; it's REX.
+  void decl(Reg32 r)  { instrR(instr_dec,  r); }
+  void decw(Reg16 r)  { instrR(instr_dec,  r); }
   void notb(Reg8 r)   { instrR(instr_notb, r); }
   void not(Reg64 r)   { instrR(instr_not,  r); }
   void neg(Reg64 r)   { instrR(instr_neg,  r); }
diff --git a/hphp/util/test/asm.cpp b/hphp/util/test/asm.cpp
index 3d50cb341b2..0faa652f74c 100644
--- a/hphp/util/test/asm.cpp
+++ b/hphp/util/test/asm.cpp
@@ -510,6 +510,41 @@ TEST(Asm, RetImmediate) {
   ASSERT_FALSE(a.code.base[0] == kOpsizePrefix);
 }
 
+TEST(Asm, IncDecRegs) {
+  Asm a;
+  a.init(10 << 24);
+
+  // incq, incl, incw
+  a.    incq(rax);
+  a.    incl(eax);
+  a.    incw(ax);
+  a.    incq(r15);
+  a.    incl(r15d);
+  a.    incw(r15w);
+  // decq, decl, decw
+  a.    decq(rax);
+  a.    decl(eax);
+  a.    decw(ax);
+  a.    decq(r15);
+  a.    decl(r15d);
+  a.    decw(r15w);
+
+  expect_asm(a, R"(
+inc %rax
+inc %eax
+inc %ax
+inc %r15
+inc %r15d
+inc %r15w
+dec %rax
+dec %eax
+dec %ax
+dec %r15
+dec %r15d
+dec %r15w
+)");
+}
+
 TEST(Asm, HighByteReg) {
   Asm a;
   a.init(10 << 24);
-- 
2.11.4.GIT