Teach ScalarEvolution how to reason about no-wrap flags on loops
where the induction variable has a non-unit stride, such as {0,+,2}, and
there are expressions such as {1,+,2} inside the loop formed with
or or add nsw operators.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82151 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Analysis/ScalarEvolution/nsw-offset.ll b/test/Analysis/ScalarEvolution/nsw-offset.ll
new file mode 100644
index 0000000..1e165bf6
--- /dev/null
+++ b/test/Analysis/ScalarEvolution/nsw-offset.ll
@@ -0,0 +1,76 @@
+; RUN: opt < %s -S -analyze -scalar-evolution -disable-output | FileCheck %s
+
+; ScalarEvolution should be able to fold away the sign-extensions
+; on this loop with a primary induction variable incremented with
+; a nsw add of 2.
+
+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"
+
+define void @foo(i32 %n, double* nocapture %d, double* nocapture %q) nounwind {
+entry:
+ %0 = icmp sgt i32 %n, 0 ; <i1> [#uses=1]
+ br i1 %0, label %bb.nph, label %return
+
+bb.nph: ; preds = %entry
+ br label %bb
+
+bb: ; preds = %bb.nph, %bb1
+ %i.01 = phi i32 [ %16, %bb1 ], [ 0, %bb.nph ] ; <i32> [#uses=5]
+
+; CHECK: %1 = sext i32 %i.01 to i64
+; CHECK: --> {0,+,2}<bb>
+ %1 = sext i32 %i.01 to i64 ; <i64> [#uses=1]
+
+; CHECK: %2 = getelementptr inbounds double* %d, i64 %1
+; CHECK: --> {%d,+,16}<bb>
+ %2 = getelementptr inbounds double* %d, i64 %1 ; <double*> [#uses=1]
+
+ %3 = load double* %2, align 8 ; <double> [#uses=1]
+ %4 = sext i32 %i.01 to i64 ; <i64> [#uses=1]
+ %5 = getelementptr inbounds double* %q, i64 %4 ; <double*> [#uses=1]
+ %6 = load double* %5, align 8 ; <double> [#uses=1]
+ %7 = or i32 %i.01, 1 ; <i32> [#uses=1]
+
+; CHECK: %8 = sext i32 %7 to i64
+; CHECK: --> {1,+,2}<bb>
+ %8 = sext i32 %7 to i64 ; <i64> [#uses=1]
+
+; CHECK: %9 = getelementptr inbounds double* %q, i64 %8
+; CHECK: {(8 + %q),+,16}<bb>
+ %9 = getelementptr inbounds double* %q, i64 %8 ; <double*> [#uses=1]
+
+; Artificially repeat the above three instructions, this time using
+; add nsw instead of or.
+ %t7 = add nsw i32 %i.01, 1 ; <i32> [#uses=1]
+
+; CHECK: %t8 = sext i32 %t7 to i64
+; CHECK: --> {1,+,2}<bb>
+ %t8 = sext i32 %t7 to i64 ; <i64> [#uses=1]
+
+; CHECK: %t9 = getelementptr inbounds double* %q, i64 %t8
+; CHECK: {(8 + %q),+,16}<bb>
+ %t9 = getelementptr inbounds double* %q, i64 %t8 ; <double*> [#uses=1]
+
+ %10 = load double* %9, align 8 ; <double> [#uses=1]
+ %11 = fadd double %6, %10 ; <double> [#uses=1]
+ %12 = fadd double %11, 3.200000e+00 ; <double> [#uses=1]
+ %13 = fmul double %3, %12 ; <double> [#uses=1]
+ %14 = sext i32 %i.01 to i64 ; <i64> [#uses=1]
+ %15 = getelementptr inbounds double* %d, i64 %14 ; <double*> [#uses=1]
+ store double %13, double* %15, align 8
+ %16 = add nsw i32 %i.01, 2 ; <i32> [#uses=2]
+ br label %bb1
+
+bb1: ; preds = %bb
+ %17 = icmp slt i32 %16, %n ; <i1> [#uses=1]
+ br i1 %17, label %bb, label %bb1.return_crit_edge
+
+bb1.return_crit_edge: ; preds = %bb1
+ br label %return
+
+return: ; preds = %bb1.return_crit_edge, %entry
+ ret void
+}
+
+; CHECK: Loop bb: backedge-taken count is ((-1 + %n) /u 2)
+; CHECK: Loop bb: max backedge-taken count is 1073741823