llvm-6502/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-1.ll
Dan Gohman a10756ee65 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
2010-01-21 02:09:26 +00:00

27 lines
1.0 KiB
LLVM

; RUN: llc %s -o - --x86-asm-syntax=att | grep {cmp. \$8}
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"
target triple = "x86_64-apple-darwin9"
; The comparison happens after the relevant use, so the stride can easily
; be changed. The comparison can be done in a narrower mode than the
; induction variable.
define void @foo() nounwind {
entry:
br label %loop
loop:
%indvar = phi i32 [ 0, %entry ], [ %i.2.0.us1534, %loop ] ; <i32> [#uses=1]
%i.2.0.us1534 = add i32 %indvar, 1 ; <i32> [#uses=3]
%tmp628.us1540 = shl i32 %i.2.0.us1534, 1 ; <i32> [#uses=1]
%tmp645646647.us1547 = sext i32 %tmp628.us1540 to i64 ; <i64> [#uses=1]
store i64 %tmp645646647.us1547, i64* null
%tmp611.us1535 = icmp eq i32 %i.2.0.us1534, 4 ; <i1> [#uses=2]
%tmp623.us1538 = select i1 %tmp611.us1535, i32 6, i32 0 ; <i32> [#uses=1]
store i32 %tmp623.us1538, i32* null
br i1 %tmp611.us1535, label %exit, label %loop
exit:
ret void
}