[ADT] Micro-optimize the Triple constructor by doing a single split and

re-using the resulting components rather than repeatedly splitting and
re-splitting to compute each component as part of the initializer list.

This is more work on PR23676. Sadly, it doesn't help much. It removes
the constructor from my profile, but doesn't make a sufficient dent in
the total time. But it should play together nicely with subsequent
changes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@247250 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Support/Triple.cpp b/lib/Support/Triple.cpp
index dfe719d1f113b100aa5959e201d8da5560a633a6..32fabd4dae169c3ebda7ad7abe38e0c7a78a6b3a 100644 (file)
--- a/lib/Support/Triple.cpp
+++ b/lib/Support/Triple.cpp
@@ -572,14 +572,27 @@ static Triple::ObjectFormatType getDefaultFormat(const Triple &T) {
 /// This stores the string representation and parses the various pieces into
 /// enum members.
 Triple::Triple(const Twine &Str)
-    : Data(Str.str()),
-      Arch(parseArch(getArchName())),
-      SubArch(parseSubArch(getArchName())),
-      Vendor(parseVendor(getVendorName())),
-      OS(parseOS(getOSName())),
-      Environment(parseEnvironment(getEnvironmentName())),
-      ObjectFormat(parseFormat(getEnvironmentName())) {
-  if (ObjectFormat == Triple::UnknownObjectFormat)
+    : Data(Str.str()), Arch(UnknownArch), SubArch(NoSubArch),
+      Vendor(UnknownVendor), OS(UnknownOS), Environment(UnknownEnvironment),
+      ObjectFormat(UnknownObjectFormat) {
+  // Do minimal parsing by hand here.
+  SmallVector<StringRef, 4> Components;
+  StringRef(Data).split(Components, '-', /*MaxSplit*/ 3);
+  if (Components.size() > 0) {
+    Arch = parseArch(Components[0]);
+    SubArch = parseSubArch(Components[0]);
+    if (Components.size() > 1) {
+      Vendor = parseVendor(Components[1]);
+      if (Components.size() > 2) {
+        OS = parseOS(Components[2]);
+        if (Components.size() > 3) {
+          Environment = parseEnvironment(Components[3]);
+          ObjectFormat = parseFormat(Components[3]);
+        }
+      }
+    }
+  }
+  if (ObjectFormat == UnknownObjectFormat)
     ObjectFormat = getDefaultFormat(*this);
 }