[llvm] r313815 - [mips] Fix calculation of a branch instruction offset to escape left shift of negative value

[Simon Atanasyan via llvm-commits]

Author: atanasyan
Date: Wed Sep 20 14:01:30 2017
New Revision: 313815

URL: http://llvm.org/viewvc/llvm-project?rev=313815&view=rev
Log:
[mips] Fix calculation of a branch instruction offset to escape left shift of negative value

Modified:
    llvm/trunk/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
    llvm/trunk/test/MC/Mips/micromips-neg-offset.s

Modified: llvm/trunk/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Mips/Disassembler/MipsDisassembler.cpp?rev=313815&r1=313814&r2=313815&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Mips/Disassembler/MipsDisassembler.cpp (original)
+++ llvm/trunk/lib/Target/Mips/Disassembler/MipsDisassembler.cpp Wed Sep 20 14:01:30 2017
@@ -2278,7 +2278,7 @@ static DecodeStatus DecodeBranchTarget7M
                                           unsigned Offset,
                                           uint64_t Address,
                                           const void *Decoder) {
-  int32_t BranchOffset = SignExtend32<7>(Offset) << 1;
+  int32_t BranchOffset = SignExtend32<8>(Offset << 1);
   Inst.addOperand(MCOperand::createImm(BranchOffset));
   return MCDisassembler::Success;
 }
@@ -2287,7 +2287,7 @@ static DecodeStatus DecodeBranchTarget10
                                            unsigned Offset,
                                            uint64_t Address,
                                            const void *Decoder) {
-  int32_t BranchOffset = SignExtend32<10>(Offset) << 1;
+  int32_t BranchOffset = SignExtend32<11>(Offset << 1);
   Inst.addOperand(MCOperand::createImm(BranchOffset));
   return MCDisassembler::Success;
 }
@@ -2305,7 +2305,7 @@ static DecodeStatus DecodeBranchTarget26
   unsigned Offset,
   uint64_t Address,
   const void *Decoder) {
-  int32_t BranchOffset = SignExtend32<26>(Offset) << 1;
+  int32_t BranchOffset = SignExtend32<27>(Offset << 1);
 
   Inst.addOperand(MCOperand::createImm(BranchOffset));
   return MCDisassembler::Success;

Modified: llvm/trunk/test/MC/Mips/micromips-neg-offset.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/Mips/micromips-neg-offset.s?rev=313815&r1=313814&r2=313815&view=diff
==============================================================================
--- llvm/trunk/test/MC/Mips/micromips-neg-offset.s (original)
+++ llvm/trunk/test/MC/Mips/micromips-neg-offset.s Wed Sep 20 14:01:30 2017
@@ -1,8 +1,13 @@
 # Check decoding beqz instruction with a negative offset
 
-# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux -mattr=micromips %s -o - \
+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux \
+# RUN:         -mattr=micromips -mcpu=mips32r6 %s -o - \
 # RUN:   | llvm-objdump -d -mattr=micromips - | FileCheck %s
 
-# CHECK: 0:   8f 7e   beqz16  $6, -4
+# CHECK: 0:   8f 7e        beqzc16  $6, -4
+# CHECK: 6:   cf fe        bc16     -4
+# CHECK: c:   b7 ff ff fe  balc     -4
 
 beqz16  $6, -4
+b16     -4
+balc    -4