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-rw-r--r--src/arch/x86/predecoder.cc16
1 files changed, 13 insertions, 3 deletions
diff --git a/src/arch/x86/predecoder.cc b/src/arch/x86/predecoder.cc
index 295ca10a4..7f8bc7abc 100644
--- a/src/arch/x86/predecoder.cc
+++ b/src/arch/x86/predecoder.cc
@@ -311,9 +311,19 @@ namespace X86ISA
else
displacementSize = 0;
}
+
+ // The "test" instruction in group 3 needs an immediate, even though
+ // the other instructions with the same actual opcode don't.
+ if (emi.opcode.num == 1 && (modRM.reg & 0x6) == 0) {
+ if (emi.opcode.op == 0xF6)
+ immediateSize = 1;
+ else if (emi.opcode.op == 0xF7)
+ immediateSize = (emi.opSize == 8) ? 4 : emi.opSize;
+ }
+
//If there's an SIB, get that next.
//There is no SIB in 16 bit mode.
- if(modRM.rm == 4 && modRM.mod != 3) {
+ if (modRM.rm == 4 && modRM.mod != 3) {
// && in 32/64 bit mode)
nextState = SIBState;
} else if(displacementSize) {
@@ -339,9 +349,9 @@ namespace X86ISA
emi.sib = nextByte;
DPRINTF(Predecoder, "Found SIB byte %#x.\n", nextByte);
consumeByte();
- if(emi.modRM.mod == 0 && emi.sib.base == 5)
+ if (emi.modRM.mod == 0 && emi.sib.base == 5)
displacementSize = 4;
- if(displacementSize) {
+ if (displacementSize) {
nextState = DisplacementState;
} else if(immediateSize) {
nextState = ImmediateState;