[ELF, LinkerScript] Memory region name parsing fix

[meadori]

Summary

This patch fixes a small issue with respect to how memory region names
are parsed on output section descriptions. For example, consider:

.text : { *(.text) } > rom

That can also be written like:

.text : { *(.text) } >rom

The latter form is accepted by GNU LD and is fairly common.

[ruiu]

LGTM

lld/trunk/ELF/ScriptParser.cpp

if (Tok == ";") {
       Cmd->Commands.push_back(readInputSectionDescription(Tok));
     } else {
       setError("unknown command " + Tok);
     }
   }
 
   if (consume(">"))
     Cmd->MemoryRegionName = next();
+  else if (peek().startswith(">"))
+    Cmd->MemoryRegionName = next().drop_front();
 
   Cmd->Phdrs = readOutputSectionPhdrs();
 
   if (consume("="))
     Cmd->Filler = parseFill(next());
   else if (peek().startswith("="))
     Cmd->Filler = parseFill(next().drop_front());
 

lld/trunk/test/ELF/linkerscript/memory.s

 
 ## Check RAM and ROM memory regions.
 
 # RUN: echo "MEMORY { \
 # RUN:   ram (rwx) : ORIGIN = 0, LENGTH = 1024M \
 # RUN:   rom (rx) : org = (0x80 * 0x1000 * 0x1000), len = 64M \
 # RUN: } \
 # RUN: SECTIONS { \
-# RUN:   .text : { *(.text) } > rom \
-# RUN:   .data : { *(.data) } > ram \
+# RUN:   .text : { *(.text) } >rom \
+# RUN:   .data : { *(.data) } >ram \
 # RUN: }" > %t.script
 # RUN: ld.lld -o %t1 --script %t.script %t
 # RUN: llvm-objdump -section-headers %t1 | FileCheck -check-prefix=RAMROM %s
 
 # RAMROM:       1 .text         00000001 0000000080000000 TEXT DATA
 # RAMROM-NEXT:  2 .data         00001000 0000000000000000 DATA
 
 ## Check memory region placement by attributes.