[SCEV] Simplify trunc-of-add/mul to add/mul-of-trunc under more circumstances.

Summary:
Previously we would do this simplification only if it did not introduce
any new truncs (excepting new truncs which replace other cast ops).

This change weakens this condition: If the number of truncs stays the
same, but we're able to transform trunc(X + Y) to X + trunc(Y), that's
still simpler, and it may open up additional transformations.

While we're here, also clean up some duplicated code.

Reviewers: sanjoy

Subscribers: hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D48160

llvm-svn: 334736

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/test/Analysis/ScalarEvolution/strip-injective-zext.ll b/llvm/test/Analysis/ScalarEvolution/strip-injective-zext.ll
index 661b48f6fe5..b618b71a358 100644
--- a/llvm/test/Analysis/ScalarEvolution/strip-injective-zext.ll
+++ b/llvm/test/Analysis/ScalarEvolution/strip-injective-zext.ll
@@ -9,7 +9,7 @@
 
 ; Check that the backedge taken count was actually computed:
 ; CHECK: Determining loop execution counts for: @f0
-; CHECK-NEXT: Loop %b2: backedge-taken count is (-1 * (trunc i32 (1 + %a1) to i2))
+; CHECK-NEXT: Loop %b2: backedge-taken count is (-1 + (-1 * (trunc i32 %a1 to i2)))
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64"