check first byte earlier

Author: luke-li-2003

runtime/compiler/p/codegen/J9TreeEvaluator.cpp

@@ -11747,11 +11747,6 @@ static TR::Register *inlineStringCodingHasNegativesOrCountPositives(TR::Node *no
                                      TR::Compiler->om.contiguousArrayHeaderSizeInBytes());
       }
 
-   // get the starting address
-   generateTrg1Src2Instruction(cg, TR::InstOpCode::add, node, startReg, startReg, indexReg);
-   // make the index 0 since everything we need is relative to the offset
-   generateTrg1ImmInstruction(cg, TR::InstOpCode::li, node, indexReg, 0);
-
    // check the first byte
    generateTrg1MemInstruction(cg, TR::InstOpCode::lbzx, node, tempReg,
       TR::MemoryReference::createWithIndexReg(cg, startReg, indexReg, 1));
@@ -11762,6 +11757,9 @@ static TR::Register *inlineStringCodingHasNegativesOrCountPositives(TR::Node *no
    else // when seeking negatives, we need to return 1
       generateConditionalBranchInstruction(cg, TR::InstOpCode::blt, node, matchLabel, cr6);
 
+   // count from the offset position since we are supposed to return (index-offset)
+   generateTrg1Src2Instruction(cg, TR::InstOpCode::add, node, startReg, startReg, indexReg);
+   generateTrg1ImmInstruction(cg, TR::InstOpCode::li, node, indexReg, 1);
    // if we only have one byte end it here, and return 0 for hasNegative
    generateTrg1Src1ImmInstruction(cg, TR::InstOpCode::addi, node, indexReg, indexReg, 1);
    generateTrg1Src2Instruction(cg, TR::InstOpCode::cmp4, node, cr6, indexReg, lengthReg);