[X86] Limit vpermil2pd/vpermil2ps immediates to 4 bits in the assembly parser.

The upper 4 bits of the immediate byte are used to encode a
register. We need to limit the explicit immediate to fit in the
remaining 4 bits.

Fixes PR42899.

llvm-svn: 368123

2 files changed, 13 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmParserCommon.h b/llvm/lib/Target/X86/AsmParser/X86AsmParserCommon.h
index 5bc979d1f18..e9be28ca77b 100644
--- a/llvm/lib/Target/X86/AsmParser/X86AsmParserCommon.h
+++ b/llvm/lib/Target/X86/AsmParser/X86AsmParserCommon.h
@@ -35,6 +35,10 @@ inline bool isImmUnsignedi8Value(uint64_t Value) {
   return isUInt<8>(Value) || isInt<8>(Value);
 }
 
+inline bool isImmUnsignedi4Value(uint64_t Value) {
+  return isUInt<4>(Value);
+}
+
 } // End of namespace llvm
 
 #endif
diff --git a/llvm/lib/Target/X86/AsmParser/X86Operand.h b/llvm/lib/Target/X86/AsmParser/X86Operand.h
index a771ba36631..591e6f4102f 100644
--- a/llvm/lib/Target/X86/AsmParser/X86Operand.h
+++ b/llvm/lib/Target/X86/AsmParser/X86Operand.h
@@ -260,6 +260,15 @@ struct X86Operand final : public MCParsedAsmOperand {
     return isImmSExti64i32Value(CE->getValue());
   }
 
+  bool isImmUnsignedi4() const {
+    if (!isImm()) return false;
+    // If this isn't a constant expr, just assume it fits and let relaxation
+    // handle it.
+    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
+    if (!CE) return true;
+    return isImmUnsignedi4Value(CE->getValue());
+  }
+
   bool isImmUnsignedi8() const {
     if (!isImm()) return false;
     // If this isn't a constant expr, just assume it fits and let relaxation