[polly] r288521 - Allow to disable unsigned operations (zext, icmp ugt, ...)

[Johannes Doerfert via llvm-commits]

Author: jdoerfert
Date: Fri Dec  2 11:55:41 2016
New Revision: 288521

URL: http://llvm.org/viewvc/llvm-project?rev=288521&view=rev
Log:
Allow to disable unsigned operations (zext, icmp ugt, ...)

Unsigned operations are often useful to support but the heuristics are
not yet tuned. This options allows to disable them if necessary.

Modified:
    polly/trunk/include/polly/ScopDetection.h
    polly/trunk/lib/Analysis/ScopDetection.cpp
    polly/trunk/lib/Support/SCEVValidator.cpp

Modified: polly/trunk/include/polly/ScopDetection.h
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/include/polly/ScopDetection.h?rev=288521&r1=288520&r2=288521&view=diff
==============================================================================
--- polly/trunk/include/polly/ScopDetection.h (original)
+++ polly/trunk/include/polly/ScopDetection.h Fri Dec  2 11:55:41 2016
@@ -111,6 +111,7 @@ extern bool PollyDelinearize;
 extern bool PollyUseRuntimeAliasChecks;
 extern bool PollyProcessUnprofitable;
 extern bool PollyInvariantLoadHoisting;
+extern bool PollyAllowUnsignedOperations;
 
 /// A function attribute which will cause Polly to skip the function
 extern llvm::StringRef PollySkipFnAttr;

Modified: polly/trunk/lib/Analysis/ScopDetection.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/ScopDetection.cpp?rev=288521&r1=288520&r2=288521&view=diff
==============================================================================
--- polly/trunk/lib/Analysis/ScopDetection.cpp (original)
+++ polly/trunk/lib/Analysis/ScopDetection.cpp Fri Dec  2 11:55:41 2016
@@ -109,6 +109,13 @@ static cl::opt<bool>
                    cl::Hidden, cl::init(false), cl::ZeroOrMore,
                    cl::cat(PollyCategory));
 
+bool polly::PollyAllowUnsignedOperations;
+static cl::opt<bool, true> XPollyAllowUnsignedOperations(
+    "polly-allow-unsigned-operations",
+    cl::desc("Allow unsigned operations such as comparisons or zero-extends."),
+    cl::location(PollyAllowUnsignedOperations), cl::Hidden, cl::ZeroOrMore,
+    cl::init(true), cl::cat(PollyCategory));
+
 bool polly::PollyUseRuntimeAliasChecks;
 static cl::opt<bool, true> XPollyUseRuntimeAliasChecks(
     "polly-use-runtime-alias-checks",
@@ -454,6 +461,11 @@ bool ScopDetection::isValidBranch(BasicB
   const SCEV *LHS = SE->getSCEVAtScope(ICmp->getOperand(0), L);
   const SCEV *RHS = SE->getSCEVAtScope(ICmp->getOperand(1), L);
 
+  // If unsigned operations are not allowed try to approximate the region.
+  if (ICmp->isUnsigned() && !PollyAllowUnsignedOperations)
+    return !IsLoopBranch && AllowNonAffineSubRegions &&
+           addOverApproximatedRegion(RI->getRegionFor(&BB), Context);
+
   // Check for invalid usage of different pointers in one expression.
   if (ICmp->isEquality() && involvesMultiplePtrs(LHS, nullptr, L) &&
       involvesMultiplePtrs(RHS, nullptr, L))

Modified: polly/trunk/lib/Support/SCEVValidator.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Support/SCEVValidator.cpp?rev=288521&r1=288520&r2=288521&view=diff
==============================================================================
--- polly/trunk/lib/Support/SCEVValidator.cpp (original)
+++ polly/trunk/lib/Support/SCEVValidator.cpp Fri Dec  2 11:55:41 2016
@@ -135,12 +135,27 @@ public:
     return ValidatorResult(SCEVType::INT);
   }
 
+  class ValidatorResult visitZeroExtendOrTruncateExpr(const SCEV *Expr,
+                                                      const SCEV *Operand) {
+    ValidatorResult Op = visit(Operand);
+    auto Type = Op.getType();
+
+    // If unsigned operations are allowed return the operand, otherwise
+    // check if we can model the expression without unsigned assumptions.
+    if (PollyAllowUnsignedOperations || Type == SCEVType::INVALID)
+      return Op;
+
+    if (Type == SCEVType::IV)
+      return ValidatorResult(SCEVType::INVALID);
+    return ValidatorResult(SCEVType::PARAM, Expr);
+  }
+
   class ValidatorResult visitTruncateExpr(const SCEVTruncateExpr *Expr) {
-    return visit(Expr->getOperand());
+    return visitZeroExtendOrTruncateExpr(Expr, Expr->getOperand());
   }
 
   class ValidatorResult visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
-    return visit(Expr->getOperand());
+    return visitZeroExtendOrTruncateExpr(Expr, Expr->getOperand());
   }
 
   class ValidatorResult visitSignExtendExpr(const SCEVSignExtendExpr *Expr) {
@@ -325,6 +340,9 @@ public:
   }
 
   ValidatorResult visitUDivExpr(const SCEVUDivExpr *Expr) {
+    if (!PollyAllowUnsignedOperations)
+      return ValidatorResult(SCEVType::INVALID);
+
     auto *Dividend = Expr->getLHS();
     auto *Divisor = Expr->getRHS();
     return visitDivision(Dividend, Divisor, Expr);