Re-implement the main strength-reduction portion of LoopStrengthReduction.
This new version is much more aggressive about doing "full" reduction in
cases where it reduces register pressure, and also more aggressive about
rewriting induction variables to count down (or up) to zero when doing so
reduces register pressure.
It currently uses fairly simplistic algorithms for finding reuse
opportunities, but it introduces a new framework allows it to combine
multiple strategies at once to form hybrid solutions, instead of doing
all full-reduction or all base+index.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94061 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/X86/loop-strength-reduce4.ll b/test/CodeGen/X86/loop-strength-reduce4.ll
index 07e46ec..6c0eb8c 100644
--- a/test/CodeGen/X86/loop-strength-reduce4.ll
+++ b/test/CodeGen/X86/loop-strength-reduce4.ll
@@ -1,5 +1,19 @@
-; RUN: llc < %s -march=x86 | grep cmp | grep 64
-; RUN: llc < %s -march=x86 | not grep inc
+; RUN: llc < %s -march=x86 -relocation-model=static -mtriple=i686-apple-darwin | FileCheck %s -check-prefix=STATIC
+; RUN: llc < %s -march=x86 -relocation-model=pic | FileCheck %s -check-prefix=PIC
+
+; By starting the IV at -64 instead of 0, a cmp is eliminated,
+; as the flags from the add can be used directly.
+
+; STATIC: movl $-64, %ecx
+
+; STATIC: movl %eax, _state+76(%ecx)
+; STATIC: addl $16, %ecx
+; STATIC: jne
+
+; In PIC mode the symbol can't be folded, so the change-compare-stride
+; trick applies.
+
+; PIC: cmpl $64
@state = external global [0 x i32] ; <[0 x i32]*> [#uses=4]
@S = external global [0 x i32] ; <[0 x i32]*> [#uses=4]