[llvm] r246378 - Stop calling the flat out insane ARM target parsing code unless the

[Chandler Carruth via llvm-commits]

Author: chandlerc
Date: Sun Aug 30 04:54:34 2015
New Revision: 246378

URL: http://llvm.org/viewvc/llvm-project?rev=246378&view=rev
Log:
Stop calling the flat out insane ARM target parsing code unless the
architecture string is something quite weird. Similarly delay calling
the BPF parsing code, although that is more reasonable.

To understand why I was motivated to make this change, it cuts the time
for running the ADT TripleTest unittests by a factor of two in
non-optimized builds (the developer default) and reduces my 'check-llvm'
time by a full 15 seconds. The implementation of parseARMArch is *that*
slow. I tried to fix it in the prior series of commits, but frankly,
I have no idea how to finish fixing it. The entire premise of the
function (to allow 'v7a-unknown-linux' or some such to parse as an
'arm-unknown-linux' triple) seems completely insane to me, but I'll let
the ARM folks sort that out. At least it is now out of the critical path
of every developer working on LLVM. It also will likely make some other
folks' code significantly faster as I've heard reports of 2% of time
spent in triple parsing even in optimized builds!

I'm not done making this code faster, but I am done trying to improve
the ARM target parsing code.

Modified:
    llvm/trunk/lib/Support/Triple.cpp

Modified: llvm/trunk/lib/Support/Triple.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Triple.cpp?rev=246378&r1=246377&r2=246378&view=diff
==============================================================================
--- llvm/trunk/lib/Support/Triple.cpp (original)
+++ llvm/trunk/lib/Support/Triple.cpp Sun Aug 30 04:54:34 2015
@@ -325,10 +325,7 @@ static Triple::ArchType parseARMArch(Str
 }
 
 static Triple::ArchType parseArch(StringRef ArchName) {
-  Triple::ArchType ARMArch(parseARMArch(ArchName));
-  Triple::ArchType BPFArch(parseBPFArch(ArchName));
-
-  return StringSwitch<Triple::ArchType>(ArchName)
+  auto AT = StringSwitch<Triple::ArchType>(ArchName)
     .Cases("i386", "i486", "i586", "i686", Triple::x86)
     // FIXME: Do we need to support these?
     .Cases("i786", "i886", "i986", Triple::x86)
@@ -338,9 +335,13 @@ static Triple::ArchType parseArch(String
     .Case("powerpc64le", Triple::ppc64le)
     .Case("xscale", Triple::arm)
     .Case("xscaleeb", Triple::armeb)
-    .StartsWith("arm", ARMArch)
-    .StartsWith("thumb", ARMArch)
-    .StartsWith("aarch64", ARMArch)
+    .Case("aarch64", Triple::aarch64)
+    .Case("aarch64_be", Triple::aarch64_be)
+    .Case("arm64", Triple::aarch64)
+    .Case("arm", Triple::arm)
+    .Case("armeb", Triple::armeb)
+    .Case("thumb", Triple::thumb)
+    .Case("thumbeb", Triple::thumbeb)
     .Case("msp430", Triple::msp430)
     .Cases("mips", "mipseb", "mipsallegrex", Triple::mips)
     .Cases("mipsel", "mipsallegrexel", Triple::mipsel)
@@ -348,7 +349,6 @@ static Triple::ArchType parseArch(String
     .Case("mips64el", Triple::mips64el)
     .Case("r600", Triple::r600)
     .Case("amdgcn", Triple::amdgcn)
-    .StartsWith("bpf", BPFArch)
     .Case("hexagon", Triple::hexagon)
     .Case("s390x", Triple::systemz)
     .Case("sparc", Triple::sparc)
@@ -371,6 +371,18 @@ static Triple::ArchType parseArch(String
     .Case("wasm32", Triple::wasm32)
     .Case("wasm64", Triple::wasm64)
     .Default(Triple::UnknownArch);
+
+  // Some architectures require special parsing logic just to compute the
+  // ArchType result.
+  if (AT == Triple::UnknownArch) {
+    if (ArchName.startswith("arm") || ArchName.startswith("thumb") ||
+        ArchName.startswith("aarch64"))
+      return parseARMArch(ArchName);
+    if (ArchName.startswith("bpf"))
+      return parseBPFArch(ArchName);
+  }
+
+  return AT;
 }
 
 static Triple::VendorType parseVendor(StringRef VendorName) {