llvm-6502/test/Transforms/IndVarSimplify/lcssa-preservation.ll
Wei Mi 61897e8564 Enable exitValue rewrite only when the cost of expansion is low.
The patch evaluates the expansion cost of exitValue in indVarSimplify pass, and only does the rewriting when the expansion cost is low or loop can be deleted with the rewriting. It provides an option "-replexitval=" to control the default aggressiveness of the exitvalue rewriting. It also fixes some missing cases in SCEVExpander::isHighCostExpansionHelper to enhance the evaluation of SCEV expansion cost.

Differential Revision: http://reviews.llvm.org/D9800


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238507 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-28 21:49:07 +00:00

51 lines
1.6 KiB
LLVM

; RUN: opt < %s -indvars -replexitval=always -S | FileCheck %s
; Make sure IndVars preserves LCSSA form, especially across loop nests.
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"
define void @PR18642(i32 %x) {
; CHECK-LABEL: @PR18642(
entry:
br label %outer.header
; CHECK: br label %outer.header
outer.header:
; CHECK: outer.header:
%outer.iv = phi i32 [ 0, %entry ], [ %x, %outer.latch ]
br label %inner.header
; CHECK: %[[SCEV_EXPANDED:.*]] = add i32
; CHECK: br label %inner.header
inner.header:
; CHECK: inner.header:
%inner.iv = phi i32 [ undef, %outer.header ], [ %inc, %inner.latch ]
%cmp1 = icmp slt i32 %inner.iv, %outer.iv
br i1 %cmp1, label %inner.latch, label %outer.latch
; CHECK: br i1 {{.*}}, label %inner.latch, label %outer.latch
inner.latch:
; CHECK: inner.latch:
%inc = add nsw i32 %inner.iv, 1
%cmp2 = icmp slt i32 %inner.iv, %outer.iv
br i1 %cmp2, label %inner.header, label %exit
; CHECK: br i1 {{.*}}, label %inner.header, label %[[EXIT_FROM_INNER:.*]]
outer.latch:
; CHECK: outer.latch:
br i1 undef, label %outer.header, label %exit
; CHECK: br i1 {{.*}}, label %outer.header, label %[[EXIT_FROM_OUTER:.*]]
; CHECK: [[EXIT_FROM_INNER]]:
; CHECK-NEXT: %[[LCSSA:.*]] = phi i32 [ %[[SCEV_EXPANDED]], %inner.latch ]
; CHECK-NEXT: br label %exit
; CHECK: [[EXIT_FROM_OUTER]]:
; CHECK-NEXT: br label %exit
exit:
; CHECK: exit:
%exit.phi = phi i32 [ %inc, %inner.latch ], [ undef, %outer.latch ]
; CHECK-NEXT: phi i32 [ %[[LCSSA]], %[[EXIT_FROM_INNER]] ], [ undef, %[[EXIT_FROM_OUTER]] ]
ret void
}