From 2c5291b56358bf239bdfc675ed681c2da3eb4901 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Wed, 22 Sep 2010 06:26:39 +0000
Subject: [PATCH] fix rdar://8456371 - Handle commutable instructions written
 backward.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114536 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/X86/AsmParser/X86AsmParser.cpp | 10 ++++++++++
 test/MC/AsmParser/X86/x86_instructions.s  |  8 ++++++++
 2 files changed, 18 insertions(+)

diff --git a/lib/Target/X86/AsmParser/X86AsmParser.cpp b/lib/Target/X86/AsmParser/X86AsmParser.cpp
index bb6e05c2864..01ccc50adf9 100644
--- a/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -911,6 +911,16 @@ ParseInstruction(StringRef Name, SMLoc NameLoc,
     Operands.erase(Operands.begin() + 2);
   }
 
+  // FIXME: Hack to handle "f{mul*,add*} st(0), $op" the same as
+  // "f{mul*,add*} $op", since they commute.
+  if ((Name.startswith("fmul") || Name.startswith("fadd")) &&
+      Operands.size() == 3 &&
+      static_cast<X86Operand*>(Operands[1])->isReg() &&
+      static_cast<X86Operand*>(Operands[1])->getReg() == X86::ST0) {
+    delete Operands[1];
+    Operands.erase(Operands.begin() + 1);
+  }
+  
   // FIXME: Hack to handle "imul <imm>, B" which is an alias for "imul <imm>, B,
   // B".
   if (Name.startswith("imul") && Operands.size() == 3 &&
diff --git a/test/MC/AsmParser/X86/x86_instructions.s b/test/MC/AsmParser/X86/x86_instructions.s
index aea617dff00..b72374db46f 100644
--- a/test/MC/AsmParser/X86/x86_instructions.s
+++ b/test/MC/AsmParser/X86/x86_instructions.s
@@ -353,3 +353,11 @@ mov %rdx, %cr8
 mov %rdx, %cr15
 // CHECK: movq	%rdx, %cr15
 // CHECK: encoding: [0x44,0x0f,0x22,0xfa]
+
+// rdar://8456371 - Handle commutable instructions written backward.
+// CHECK: 	faddp	%st(1)
+// CHECK:	fmulp	%st(2)
+faddp %st, %st(1)
+fmulp %st, %st(2)
+
+
-- 
2.11.0