8305690: [X86] Do not emit two REX prefixes in Assembler::prefix

lgxbslgx · lgxbslgx · commit 49726ee3a950 · 2023-04-18T08:01:32.000Z
Reviewed-by: kvn, thartmann
diff --git a/src/hotspot/cpu/x86/assembler_x86.cpp b/src/hotspot/cpu/x86/assembler_x86.cpp
@@ -12547,7 +12547,7 @@ void Assembler::prefix(Register dst, Address adr, Prefix p) {
     if (adr.index_needs_rex()) {
       assert(false, "prefix(Register dst, Address adr, Prefix p) does not support handling of an X");
     } else {
-      prefix(REX_B);
+      p = (Prefix)(p | REX_B);
     }
   } else {
     if (adr.index_needs_rex()) {

Original file line number	Diff line number	Diff line change
`@@ -12547,7 +12547,7 @@ void Assembler::prefix(Register dst, Address adr, Prefix p) {`
`12547`	`12547`	`if (adr.index_needs_rex()) {`
`12548`	`12548`	`assert(false, "prefix(Register dst, Address adr, Prefix p) does not support handling of an X");`
`12549`	`12549`	`} else {`
`12550`		`- prefix(REX_B);`
	`12550`	`+ p = (Prefix)(p \| REX_B);`
`12551`	`12551`	`}`
`12552`	`12552`	`} else {`
`12553`	`12553`	`if (adr.index_needs_rex()) {`