commit a3afcf24453123abe7c1ba3d984b19cd64b206a7
author Gheorghe-Teodor Bercea <gheorghe-teod.bercea@ibm.com> Wed Jan 09 20:38:35 2019 +0000
committer Gheorghe-Teodor Bercea <gheorghe-teod.bercea@ibm.com> Wed Jan 09 20:38:35 2019 +0000
tree 4c8968b45ab81f0718eedca561e0c3c0b0d857c1
parent 2819d4d19c88b0ec9f1d76dd3beec0aea2076a44

[OpenMP] Add flag for preventing the extension to 64 bits for the collapse loop counter

Summary: Introduce a compiler flag for cases when the user knows that the collapsed loop counter can be safely represented using at most 32 bits. This will prevent the emission of expensive mathematical operations (such as the div operation) on the iteration variable using 64 bits where 32 bit operations are sufficient.

Reviewers: ABataev, caomhin

Reviewed By: ABataev

Subscribers: hfinkel, kkwli0, guansong, cfe-commits

Differential Revision: https://reviews.llvm.org/D55928

llvm-svn: 350758

clang/lib/Sema/SemaOpenMP.cpp

diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 1166de7..89eb2e2 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -4136,7 +4136,7 @@
     if (!TestIsLessOp.hasValue())
       TestIsLessOp = IsConstPos || (IsUnsigned && !Subtract);
     if (UB && (IsConstZero ||
-               (TestIsLessOp.getValue() ? 
+               (TestIsLessOp.getValue() ?
                   (IsConstNeg || (IsUnsigned && Subtract)) :
                   (IsConstPos || (IsUnsigned && !Subtract))))) {
       SemaRef.Diag(NewStep->getExprLoc(),
@@ -4311,7 +4311,7 @@
                        Op == OO_Less || Op == OO_Greater, CE->getSourceRange(),
                        CE->getOperatorLoc());
         break;
-      case OO_ExclaimEqual: 
+      case OO_ExclaimEqual:
         return setUB(getInitLCDecl(CE->getArg(0)) == LCDecl ?
                      CE->getArg(1) : CE->getArg(0),
                      /*LessOp=*/llvm::None,
@@ -4569,7 +4569,7 @@
 
   ExprResult CondExpr =
       SemaRef.BuildBinOp(S, DefaultLoc,
-                         TestIsLessOp.getValue() ? 
+                         TestIsLessOp.getValue() ?
                            (TestIsStrictOp ? BO_LT : BO_LE) :
                            (TestIsStrictOp ? BO_GT : BO_GE),
                          NewLB.get(), NewUB.get());
@@ -5270,13 +5270,14 @@
 
   // Choose either the 32-bit or 64-bit version.
   ExprResult LastIteration = LastIteration64;
-  if (LastIteration32.isUsable() &&
-      C.getTypeSize(LastIteration32.get()->getType()) == 32 &&
-      (AllCountsNeedLessThan32Bits || NestedLoopCount == 1 ||
-       fitsInto(
-           /*Bits=*/32,
-           LastIteration32.get()->getType()->hasSignedIntegerRepresentation(),
-           LastIteration64.get(), SemaRef)))
+  if (SemaRef.getLangOpts().OpenMPOptimisticCollapse ||
+      (LastIteration32.isUsable() &&
+       C.getTypeSize(LastIteration32.get()->getType()) == 32 &&
+       (AllCountsNeedLessThan32Bits || NestedLoopCount == 1 ||
+        fitsInto(
+            /*Bits=*/32,
+            LastIteration32.get()->getType()->hasSignedIntegerRepresentation(),
+            LastIteration64.get(), SemaRef))))
     LastIteration = LastIteration32;
   QualType VType = LastIteration.get()->getType();
   QualType RealVType = VType;
@@ -13116,7 +13117,7 @@
       continue;
     }
     assert(Count < OMPMapClause::NumberOfModifiers &&
-           "Modifiers exceed the allowed number of map type modifiers"); 
+           "Modifiers exceed the allowed number of map type modifiers");
     Modifiers[Count] = MapTypeModifiers[I];
     ModifiersLoc[Count] = MapTypeModifiersLoc[I];
     ++Count;