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changeset 13586:7737fbb055b0

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check branch displacement when patching short branches
author twisti
date Thu, 09 Jan 2014 20:04:55 -0800
parents f4f0a8a01ce0
children 40e81cba9e08
files graal/com.oracle.graal.asm.amd64/src/com/oracle/graal/asm/amd64/AMD64Assembler.java
diffstat 1 files changed, 8 insertions(+), 1 deletions(-) [+]
line wrap: on
line diff
--- a/graal/com.oracle.graal.asm.amd64/src/com/oracle/graal/asm/amd64/AMD64Assembler.java	Thu Jan 09 16:18:29 2014 +0100
+++ b/graal/com.oracle.graal.asm.amd64/src/com/oracle/graal/asm/amd64/AMD64Assembler.java	Thu Jan 09 20:04:55 2014 -0800
@@ -2437,7 +2437,14 @@
         } else if (op == 0xEB || (op & 0xF0) == 0x70) {
 
             // short offset operators (jmp and jcc)
-            int imm8 = branchTarget - (branch + 2);
+            final int imm8 = branchTarget - (branch + 2);
+            /*
+             * Since a wrongly patched short branch can potentially lead to working but really bad
+             * behaving code we should always fail with an exception instead of having an assert.
+             */
+            if (!NumUtil.isByte(imm8)) {
+                throw new InternalError("branch displacement out of range: " + imm8);
+            }
             codeBuffer.emitByte(imm8, branch + 1);
 
         } else {