From 2e66afabcfd12605a9b78a34055386a62344685e Mon Sep 17 00:00:00 2001
From: Philip Reames <listmail@philipreames.com>
Date: Fri, 31 May 2019 16:54:38 +0000
Subject: [PATCH] [Tests] Add tests for loop predication of loops w/ne latch
 conditions

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@362244 91177308-0d34-0410-b5e6-96231b3b80d8
---
 test/Transforms/LoopPredication/basic.ll | 172 +++++++++++++++++++++++
 1 file changed, 172 insertions(+)

diff --git a/test/Transforms/LoopPredication/basic.ll b/test/Transforms/LoopPredication/basic.ll
index 329b13bee00..0037dcdff91 100644
--- a/test/Transforms/LoopPredication/basic.ll
+++ b/test/Transforms/LoopPredication/basic.ll
@@ -1595,3 +1595,175 @@ exit:
   %result = phi i32 [ %loop.acc.next, %loop ]
   ret i32 %result
 }
+
+; NE Check (as produced by LFTR) where we can prove Start < End via simple
+; instruction analysis
+define i32 @ne_latch_zext(i32* %array, i32 %length, i16 %n16) {
+; CHECK-LABEL: @ne_latch_zext(
+; CHECK-NEXT:  loop.preheader:
+; CHECK-NEXT:    [[N:%.*]] = zext i16 [[N16:%.*]] to i32
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[I:%.*]] = phi i32 [ [[I_NEXT:%.*]], [[LOOP]] ], [ 0, [[LOOP_PREHEADER:%.*]] ]
+; CHECK-NEXT:    [[WITHIN_BOUNDS:%.*]] = icmp ult i32 [[I]], [[LENGTH:%.*]]
+; CHECK-NEXT:    call void (i1, ...) @llvm.experimental.guard(i1 [[WITHIN_BOUNDS]], i32 9) [ "deopt"() ]
+; CHECK-NEXT:    [[I_NEXT]] = add nuw i32 [[I]], 1
+; CHECK-NEXT:    [[CONTINUE:%.*]] = icmp ne i32 [[I_NEXT]], [[N]]
+; CHECK-NEXT:    br i1 [[CONTINUE]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret i32 0
+;
+loop.preheader:
+  %n = zext i16 %n16 to i32
+  br label %loop
+
+loop:
+  %i = phi i32 [ %i.next, %loop ], [ 0, %loop.preheader ]
+  %within.bounds = icmp ult i32 %i, %length
+  call void (i1, ...) @llvm.experimental.guard(i1 %within.bounds, i32 9) [ "deopt"() ]
+
+  %i.next = add nuw i32 %i, 1
+  %continue = icmp ne i32 %i.next, %n
+  br i1 %continue, label %loop, label %exit
+
+exit:
+  ret i32 0
+}
+
+; NE Check (as produced by LFTR) where we can prove Start < End via the
+; condition guarding the loop entry.
+define i32 @ne_latch_dom_check(i32* %array, i32 %length, i32 %n) {
+; CHECK-LABEL: @ne_latch_dom_check(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp sle i32 [[N:%.*]], 0
+; CHECK-NEXT:    br i1 [[TMP5]], label [[EXIT:%.*]], label [[LOOP_PREHEADER:%.*]]
+; CHECK:       loop.preheader:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[I:%.*]] = phi i32 [ [[I_NEXT:%.*]], [[LOOP]] ], [ 0, [[LOOP_PREHEADER]] ]
+; CHECK-NEXT:    [[WITHIN_BOUNDS:%.*]] = icmp ult i32 [[I]], [[LENGTH:%.*]]
+; CHECK-NEXT:    call void (i1, ...) @llvm.experimental.guard(i1 [[WITHIN_BOUNDS]], i32 9) [ "deopt"() ]
+; CHECK-NEXT:    [[I_NEXT]] = add nuw i32 [[I]], 1
+; CHECK-NEXT:    [[CONTINUE:%.*]] = icmp ne i32 [[I_NEXT]], [[N]]
+; CHECK-NEXT:    br i1 [[CONTINUE]], label [[LOOP]], label [[EXIT_LOOPEXIT:%.*]]
+; CHECK:       exit.loopexit:
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret i32 0
+;
+entry:
+  %tmp5 = icmp sle i32 %n, 0
+  br i1 %tmp5, label %exit, label %loop.preheader
+
+loop.preheader:
+  br label %loop
+
+loop:
+  %i = phi i32 [ %i.next, %loop ], [ 0, %loop.preheader ]
+  %within.bounds = icmp ult i32 %i, %length
+  call void (i1, ...) @llvm.experimental.guard(i1 %within.bounds, i32 9) [ "deopt"() ]
+
+  %i.next = add nuw i32 %i, 1
+  %continue = icmp ne i32 %i.next, %n
+  br i1 %continue, label %loop, label %exit
+
+exit:
+  ret i32 0
+}
+
+; NE latch - can't prove (end-start) mod step == 0 (i.e. might wrap
+; around several times or even be infinite)
+define i32 @neg_ne_latch_mod_step(i32* %array, i32 %length, i16 %n16) {
+; CHECK-LABEL: @neg_ne_latch_mod_step(
+; CHECK-NEXT:  loop.preheader:
+; CHECK-NEXT:    [[N:%.*]] = zext i16 [[N16:%.*]] to i32
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[I:%.*]] = phi i32 [ [[I_NEXT:%.*]], [[LOOP]] ], [ 0, [[LOOP_PREHEADER:%.*]] ]
+; CHECK-NEXT:    [[WITHIN_BOUNDS:%.*]] = icmp ult i32 [[I]], [[LENGTH:%.*]]
+; CHECK-NEXT:    call void (i1, ...) @llvm.experimental.guard(i1 [[WITHIN_BOUNDS]], i32 9) [ "deopt"() ]
+; CHECK-NEXT:    [[I_NEXT]] = add i32 [[I]], 3
+; CHECK-NEXT:    [[CONTINUE:%.*]] = icmp ne i32 [[I_NEXT]], [[N]]
+; CHECK-NEXT:    br i1 [[CONTINUE]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret i32 0
+;
+loop.preheader:
+  %n = zext i16 %n16 to i32
+  br label %loop
+
+loop:
+  %i = phi i32 [ %i.next, %loop ], [ 0, %loop.preheader ]
+  %within.bounds = icmp ult i32 %i, %length
+  call void (i1, ...) @llvm.experimental.guard(i1 %within.bounds, i32 9) [ "deopt"() ]
+
+  %i.next = add i32 %i, 3
+  %continue = icmp ne i32 %i.next, %n
+  br i1 %continue, label %loop, label %exit
+
+exit:
+  ret i32 0
+}
+
+; NE latch - TODO: could prove (end-start) mod step == 0
+define i32 @ne_latch_mod_step(i32* %array, i32 %length) {
+; CHECK-LABEL: @ne_latch_mod_step(
+; CHECK-NEXT:  loop.preheader:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[I:%.*]] = phi i32 [ [[I_NEXT:%.*]], [[LOOP]] ], [ 0, [[LOOP_PREHEADER:%.*]] ]
+; CHECK-NEXT:    [[WITHIN_BOUNDS:%.*]] = icmp ult i32 [[I]], [[LENGTH:%.*]]
+; CHECK-NEXT:    call void (i1, ...) @llvm.experimental.guard(i1 [[WITHIN_BOUNDS]], i32 9) [ "deopt"() ]
+; CHECK-NEXT:    [[I_NEXT]] = add nuw i32 [[I]], 2
+; CHECK-NEXT:    [[CONTINUE:%.*]] = icmp ne i32 [[I_NEXT]], 400
+; CHECK-NEXT:    br i1 [[CONTINUE]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret i32 0
+;
+loop.preheader:
+  br label %loop
+
+loop:
+  %i = phi i32 [ %i.next, %loop ], [ 0, %loop.preheader ]
+  %within.bounds = icmp ult i32 %i, %length
+  call void (i1, ...) @llvm.experimental.guard(i1 %within.bounds, i32 9) [ "deopt"() ]
+
+  %i.next = add nuw i32 %i, 2
+  %continue = icmp ne i32 %i.next, 400
+  br i1 %continue, label %loop, label %exit
+
+exit:
+  ret i32 0
+}
+
+; NE Latch - but end > start so wraps around and not equivelent to a ult
+define i32 @neg_ne_latch_swapped_order(i32* %array, i32 %length) {
+; CHECK-LABEL: @neg_ne_latch_swapped_order(
+; CHECK-NEXT:  loop.preheader:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[I:%.*]] = phi i32 [ [[I_NEXT:%.*]], [[LOOP]] ], [ 400, [[LOOP_PREHEADER:%.*]] ]
+; CHECK-NEXT:    [[WITHIN_BOUNDS:%.*]] = icmp ult i32 [[I]], [[LENGTH:%.*]]
+; CHECK-NEXT:    call void (i1, ...) @llvm.experimental.guard(i1 [[WITHIN_BOUNDS]], i32 9) [ "deopt"() ]
+; CHECK-NEXT:    [[I_NEXT]] = add i32 [[I]], 1
+; CHECK-NEXT:    [[CONTINUE:%.*]] = icmp ne i32 [[I_NEXT]], 0
+; CHECK-NEXT:    br i1 [[CONTINUE]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret i32 0
+;
+loop.preheader:
+  br label %loop
+
+loop:
+  %i = phi i32 [ %i.next, %loop ], [ 400, %loop.preheader ]
+  %within.bounds = icmp ult i32 %i, %length
+  call void (i1, ...) @llvm.experimental.guard(i1 %within.bounds, i32 9) [ "deopt"() ]
+
+  %i.next = add i32 %i, 1
+  %continue = icmp ne i32 %i.next, 0
+  br i1 %continue, label %loop, label %exit
+
+exit:
+  ret i32 0
+}
+
-- 
2.50.1