r269716 - Avoid O(n^2) string analysis when handling GNU __asm__ statements.

[Richard Smith via cfe-commits]

Author: rsmith
Date: Mon May 16 17:52:23 2016
New Revision: 269716

URL: http://llvm.org/viewvc/llvm-project?rev=269716&view=rev
Log:
Avoid O(n^2) string analysis when handling GNU __asm__ statements.

Modified:
    cfe/trunk/lib/AST/Stmt.cpp

Modified: cfe/trunk/lib/AST/Stmt.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Stmt.cpp?rev=269716&r1=269715&r2=269716&view=diff
==============================================================================
--- cfe/trunk/lib/AST/Stmt.cpp (original)
+++ cfe/trunk/lib/AST/Stmt.cpp Mon May 16 17:52:23 2016
@@ -503,6 +503,9 @@ unsigned GCCAsmStmt::AnalyzeAsmString(Sm
 
   bool HasVariants = !C.getTargetInfo().hasNoAsmVariants();
 
+  unsigned LastAsmStringToken = 0;
+  unsigned LastAsmStringOffset = 0;
+
   while (1) {
     // Done with the string?
     if (CurPtr == StrEnd) {
@@ -589,10 +592,12 @@ unsigned GCCAsmStmt::AnalyzeAsmString(Sm
 
       // (BeginLoc, EndLoc) represents the range of the operand we are currently
       // processing. Unlike Str, the range includes the leading '%'.
-      SourceLocation BeginLoc =
-          getAsmString()->getLocationOfByte(Percent - StrStart, SM, LO, TI);
-      SourceLocation EndLoc =
-          getAsmString()->getLocationOfByte(CurPtr - StrStart, SM, LO, TI);
+      SourceLocation BeginLoc = getAsmString()->getLocationOfByte(
+          Percent - StrStart, SM, LO, TI, &LastAsmStringToken,
+          &LastAsmStringOffset);
+      SourceLocation EndLoc = getAsmString()->getLocationOfByte(
+          CurPtr - StrStart, SM, LO, TI, &LastAsmStringToken,
+          &LastAsmStringOffset);
 
       Pieces.emplace_back(N, std::move(Str), BeginLoc, EndLoc);
       continue;
@@ -623,10 +628,12 @@ unsigned GCCAsmStmt::AnalyzeAsmString(Sm
 
       // (BeginLoc, EndLoc) represents the range of the operand we are currently
       // processing. Unlike Str, the range includes the leading '%'.
-      SourceLocation BeginLoc =
-          getAsmString()->getLocationOfByte(Percent - StrStart, SM, LO, TI);
-      SourceLocation EndLoc =
-          getAsmString()->getLocationOfByte(NameEnd + 1 - StrStart, SM, LO, TI);
+      SourceLocation BeginLoc = getAsmString()->getLocationOfByte(
+          Percent - StrStart, SM, LO, TI, &LastAsmStringToken,
+          &LastAsmStringOffset);
+      SourceLocation EndLoc = getAsmString()->getLocationOfByte(
+          NameEnd + 1 - StrStart, SM, LO, TI, &LastAsmStringToken,
+          &LastAsmStringOffset);
 
       Pieces.emplace_back(N, std::move(Str), BeginLoc, EndLoc);