[llvm-exegesis] Avoid yaml parser from calling sscanf for obvious non-matches (PR39102)
deserializeMCOperand - ensure that we at least match the first character of the sscanf pattern before calling
This reduces llvm-exegesis uops analysis of the instructions supported from btver2 from 5m13s to 2m1s on debug builds.
llvm-svn: 343690
diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkResult.cpp b/llvm/tools/llvm-exegesis/lib/BenchmarkResult.cpp
index a3dd56c..c61d869 100644
--- a/llvm/tools/llvm-exegesis/lib/BenchmarkResult.cpp
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkResult.cpp
@@ -90,9 +90,11 @@
assert(!String.empty());
int64_t IntValue = 0;
double DoubleValue = 0;
- if (sscanf(String.data(), kIntegerFormat, &IntValue) == 1)
+ if (String[0] == kIntegerFormat[0] &&
+ sscanf(String.data(), kIntegerFormat, &IntValue) == 1)
return llvm::MCOperand::createImm(IntValue);
- if (sscanf(String.data(), kDoubleFormat, &DoubleValue) == 1)
+ if (String[0] == kDoubleFormat[0] &&
+ sscanf(String.data(), kDoubleFormat, &DoubleValue) == 1)
return llvm::MCOperand::createFPImm(DoubleValue);
if (unsigned RegNo = getRegNo(String))
return llvm::MCOperand::createReg(RegNo);