DependenceAnalysis: Don't crash if there is no constant operand.

This makes the code match the comments. Resolves a crash in loop idiom (PR14219).

llvm-svn: 167110

diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index f97f0f2..c1321b6 100644 (file)
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -2278,11 +2278,12 @@ bool DependenceAnalysis::gcdMIVtest(const SCEV *Src,
         assert(!Constant && "Surprised to find multiple constants");
         Constant = cast<SCEVConstant>(Operand);
       }
-      else if (isa<SCEVMulExpr>(Operand)) {
+      else if (const SCEVMulExpr *Product = dyn_cast<SCEVMulExpr>(Operand)) {
         // Search for constant operand to participate in GCD;
         // If none found; return false.
-        const SCEVConstant *ConstOp =
-          getConstantPart(cast<SCEVMulExpr>(Operand));
+        const SCEVConstant *ConstOp = getConstantPart(Product);
+        if (!ConstOp)
+          return false;
         APInt ConstOpValue = ConstOp->getValue()->getValue();
         ExtraGCD = APIntOps::GreatestCommonDivisor(ExtraGCD,
                                                    ConstOpValue.abs());

diff --git a/llvm/test/Transforms/LoopIdiom/crash.ll b/llvm/test/Transforms/LoopIdiom/crash.ll
new file mode 100644 (file)
index 0000000..969adbc
--- /dev/null
+++ b/llvm/test/Transforms/LoopIdiom/crash.ll
@@ -0,0 +1,25 @@
+; RUN: opt -basicaa -loop-idiom -S < %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.8.0"
+
+; Don't crash inside DependenceAnalysis
+; PR14219
+define void @test1(i64* %iwork, i64 %x)  {
+bb0:
+  %mul116 = mul nsw i64 %x, %x
+  %incdec.ptr6.sum175 = add i64 42, %x
+  %arrayidx135 = getelementptr inbounds i64* %iwork, i64 %incdec.ptr6.sum175
+  br label %bb1
+bb1:
+  %storemerge4226 = phi i64 [ 0, %bb0 ], [ %inc139, %bb1 ]
+  store i64 1, i64* %arrayidx135, align 8
+  %incdec.ptr6.sum176 = add i64 %mul116, %storemerge4226
+  %arrayidx137 = getelementptr inbounds i64* %iwork, i64 %incdec.ptr6.sum176
+  store i64 1, i64* %arrayidx137, align 8
+  %inc139 = add nsw i64 %storemerge4226, 1
+  %cmp131 = icmp sgt i64 %storemerge4226, 42
+  br i1 %cmp131, label %bb2, label %bb1
+bb2:
+  ret void
+}
+