[PATCH] D38117: [X86] [MC] fixed non optimal encoding of instruction memory operand (PR24038)

[Konstantin Belochapka via Phabricator via llvm-commits]

kbelochapka created this revision.

Fixed suboptimal encoding of instruction memory operand when assembler selected 32 bit fixup rather than 8 bit immediate for encoding memory offset value.


https://reviews.llvm.org/D38117

Files:
  lib/Target/X86/AsmParser/X86AsmParser.cpp
  test/MC/X86/x86_64-encoding.s


Index: test/MC/X86/x86_64-encoding.s
===================================================================
--- test/MC/X86/x86_64-encoding.s
+++ test/MC/X86/x86_64-encoding.s
@@ -251,3 +251,15 @@
 // CHECK: pinsrw $3, %ecx, %xmm5
 // CHECK: encoding: [0x66,0x0f,0xc4,0xe9,0x03]
           pinsrw $3, %rcx, %xmm5
+
+//CHECK   movq	12(%rdi), %rsi
+//CHECK   encoding: [0x48,0x8b,0x77,0x0c]
+    movq 	16+0-4(%rdi),%rsi
+
+//CHECK   movq	12(%rdi), %rsi
+//CHECK   encoding: [0x48,0x8b,0x77,0x0c]
+    movq 	(16+(0-4))(%rdi),%rsi
+
+//CHECK   movq	12(%rdi), %rsi
+//CHECK   encoding: [0x48,0x8b,0x77,0x0c]
+    movq 	(16+0)-1+1-2+2-3+3-4+4-5+5-6+6-(4)(%rdi),%rsi
Index: lib/Target/X86/AsmParser/X86AsmParser.cpp
===================================================================
--- lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -1985,9 +1985,12 @@
       // memory operand consumed.
     } else {
       SMLoc ExprEnd;
+      getLexer().UnLex(AsmToken(AsmToken::LParen, "("));
 
-      // It must be an parenthesized expression, parse it now.
-      if (getParser().parseParenExpression(Disp, ExprEnd))
+      // It must be either an parenthesized expression, or an expression that
+      // begins from a parenthesized expression, parse it now. Example: (1+2) or
+      // (1+2)+3
+      if (getParser().parseExpression(Disp, ExprEnd))
         return nullptr;
 
       // After parsing the base expression we could either have a parenthesized


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