MC/AsmParser: Attempt to constant fold expressions up-front. This ensures we avoid fixups for obvious cases like '-(16)'.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96064 91177308-0d34-0410-b5e6-96231b3b80d8

lib/MC/MCParser/AsmParser.cpp

@@ -325,9 +325,17 @@ bool AsmParser::ParseExpression(const MCExpr *&Res) {
 ///  expr ::= primaryexpr
 ///
 bool AsmParser::ParseExpression(const MCExpr *&Res, SMLoc &EndLoc) {
+  // Parse the expression.
   Res = 0;
-  return ParsePrimaryExpr(Res, EndLoc) ||
-         ParseBinOpRHS(1, Res, EndLoc);
+  if (ParsePrimaryExpr(Res, EndLoc) || ParseBinOpRHS(1, Res, EndLoc))
+    return true;
+
+  // Try to constant fold it up front, if possible.
+  int64_t Value;
+  if (Res->EvaluateAsAbsolute(Value))
+    Res = MCConstantExpr::Create(Value, getContext());
+
+  return false;
 }
 
 bool AsmParser::ParseParenExpression(const MCExpr *&Res, SMLoc &EndLoc) {

test/MC/AsmParser/X86/x86_32-new-encoder.s

@@ -28,3 +28,9 @@
 	swapgs
 // CHECK: swapgs
 // CHECK: encoding: [0x0f,0x01,0xf8]
+
+// CHECK: movl	%eax, 16(%ebp)          # encoding: [0x89,0x45,0x10]
+	movl	%eax, 16(%ebp)
+// CHECK: movl	%eax, -16(%ebp)          # encoding: [0x89,0x45,0xf0]
+	movl	%eax, -16(%ebp)
+        

test/MC/AsmParser/X86/x86_operands.s

@@ -5,28 +5,28 @@
 # Immediates
 # CHECK: addl $1, %eax
         addl $1, %eax
-# CHECK: addl $1+2, %eax
+# CHECK: addl $3, %eax
         addl $(1+2), %eax
 # CHECK: addl $a, %eax
         addl $a, %eax
-# CHECK: addl $1+2, %eax
+# CHECK: addl $3, %eax
         addl $1 + 2, %eax
         
 # Disambiguation
 
-        # FIXME: Add back when we can match this.
-        #addl $1, 4+4
-        # FIXME: Add back when we can match this.
-        #addl $1, (4+4)
-# CHECK: addl $1, 4+4(%eax)
+# CHECK: addl $1, 8
+        addl $1, 4+4
+# CHECK: addl $1, 8
+        addl $1, (4+4)
+# CHECK: addl $1, 8(%eax)
         addl $1, 4+4(%eax)
-# CHECK: addl $1, 4+4(%eax)
+# CHECK: addl $1, 8(%eax)
         addl $1, (4+4)(%eax)
 # CHECK: addl $1, 8(%eax)
         addl $1, 8(%eax)
 # CHECK: addl $1, (%eax)
         addl $1, (%eax)
-# CHECK: addl $1, 4+4(,%eax)
+# CHECK: addl $1, 8(,%eax)
         addl $1, (4+4)(,%eax)
         
 # Indirect Memory Operands

test/MC/AsmParser/conditional_asm.s

@@ -1,6 +1,6 @@
 # RUN: llvm-mc -triple i386-unknown-unknown %s -I  %p | FileCheck %s
 
-# CHECK: .byte 1+1
+# CHECK: .byte 2
 .if 1+2
     .if 1-1
         .byte 1