[llvm] Use StringRef::consume_front (NFC) (llvm#139458)

Author: kazutakahirata

llvm/lib/Support/APFloat.cpp

@@ -3262,9 +3262,8 @@ bool IEEEFloat::convertFromStringSpecials(StringRef str) {
     return true;
   }
 
-  bool IsNegative = str.front() == '-';
+  bool IsNegative = str.consume_front("-");
   if (IsNegative) {
-    str = str.drop_front();
     if (str.size() < MIN_NAME_SIZE)
       return false;
 
@@ -3275,16 +3274,13 @@ bool IEEEFloat::convertFromStringSpecials(StringRef str) {
   }
 
   // If we have a 's' (or 'S') prefix, then this is a Signaling NaN.
-  bool IsSignaling = str.front() == 's' || str.front() == 'S';
+  bool IsSignaling = str.consume_front_insensitive("s");
   if (IsSignaling) {
-    str = str.drop_front();
     if (str.size() < MIN_NAME_SIZE)
       return false;
   }
 
-  if (str.starts_with("nan") || str.starts_with("NaN")) {
-    str = str.drop_front(3);
-
+  if (str.consume_front("nan") || str.consume_front("NaN")) {
     // A NaN without payload.
     if (str.empty()) {
       makeNaN(IsSignaling, IsNegative);

llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp

@@ -1632,10 +1632,8 @@ SPIRVType *SPIRVGlobalRegistry::getOrCreateSPIRVTypeByName(
   auto SpirvTy = getOrCreateSPIRVType(Ty, MIRBuilder, AQ, false, true);
 
   // Handle "type*" or  "type* vector[N]".
-  if (TypeStr.starts_with("*")) {
+  if (TypeStr.consume_front("*"))
     SpirvTy = getOrCreateSPIRVPointerType(Ty, MIRBuilder, SC);
-    TypeStr = TypeStr.substr(strlen("*"));
-  }
 
   // Handle "typeN*" or  "type vector[N]*".
   bool IsPtrToVec = TypeStr.consume_back("*");