mirror of
https://github.com/RPCS3/llvm.git
synced 2025-04-06 15:21:37 +00:00
a27504ef06
Summary: It is incorrect to compare TripCount (which is BECount + 1) with extraiters (or Count) to check if we should enter unrolled loop or not, because TripCount can potentially overflow (when BECount is max unsigned integer). While comparing BECount with (Count - 1) is overflow safe and therefore correct. Reviewer: hfinkel Differential Revision: http://reviews.llvm.org/D19256 From: Evgeny Stupachenko <evstupac@gmail.com> git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267662 91177308-0d34-0410-b5e6-96231b3b80d8
50 lines
1.8 KiB
LLVM
50 lines
1.8 KiB
LLVM
; RUN: opt < %s -S -unroll-runtime -unroll-count=2 -loop-unroll | FileCheck %s -check-prefix=EPILOG
|
|
; RUN: opt < %s -S -unroll-runtime -unroll-count=2 -loop-unroll -unroll-runtime-epilog=false | FileCheck %s -check-prefix=PROLOG
|
|
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
|
|
|
|
; This test case documents how runtime loop unrolling handles the case
|
|
; when the backedge-count is -1.
|
|
|
|
; If %N, the backedge-taken count, is -1 then %0 unsigned-overflows
|
|
; and is 0. %xtraiter too is 0, signifying that the total trip-count
|
|
; is divisible by 2. The prologue then branches to the unrolled loop
|
|
; and executes the 2^32 iterations there, in groups of 2.
|
|
|
|
; EPILOG: entry:
|
|
|
|
; EPILOG-NEXT: %0 = add i32 %N, 1
|
|
; EPILOG-NEXT: %xtraiter = and i32 %0, 1
|
|
; EPILOG-NEXT: %1 = icmp ult i32 %N, 1
|
|
; EPILOG-NEXT: br i1 %1, label %while.end.unr-lcssa, label %entry.new
|
|
; EPILOG: while.body:
|
|
|
|
; EPILOG: %lcmp.mod = icmp ne i32 %xtraiter, 0
|
|
; EPILOG-NEXT: br i1 %lcmp.mod, label %while.body.epil.preheader, label %while.end
|
|
; EPILOG: while.body.epil:
|
|
|
|
; PROLOG: entry:
|
|
; PROLOG-NEXT: %0 = add i32 %N, 1
|
|
; PROLOG-NEXT: %xtraiter = and i32 %0, 1
|
|
; PROLOG-NEXT: %lcmp.mod = icmp ne i32 %xtraiter, 0
|
|
; PROLOG-NEXT: br i1 %lcmp.mod, label %while.body.prol.preheader, label %while.body.prol.loopexit
|
|
; PROLOG: while.body.prol:
|
|
|
|
; PROLOG: %1 = icmp ult i32 %N, 1
|
|
; PROLOG-NEXT: br i1 %1, label %while.end, label %entry.new
|
|
; PROLOG: while.body:
|
|
|
|
; Function Attrs: nounwind readnone ssp uwtable
|
|
define i32 @foo(i32 %N) {
|
|
entry:
|
|
br label %while.body
|
|
|
|
while.body: ; preds = %while.body, %entry
|
|
%i = phi i32 [ 0, %entry ], [ %inc, %while.body ]
|
|
%cmp = icmp eq i32 %i, %N
|
|
%inc = add i32 %i, 1
|
|
br i1 %cmp, label %while.end, label %while.body
|
|
|
|
while.end: ; preds = %while.body
|
|
ret i32 %i
|
|
}
|