From 890079ef18e1868e5b962675eeb9faac2b28d94e Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo@fhahn.com>
Date: Fri, 1 Jan 2021 13:31:23 +0000
Subject: [PATCH] [LoopLoadElim] Add tests with uncomputable BTCs.

---
 .../uncomputable-backedge-taken-count.ll           | 103 +++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 llvm/test/Transforms/LoopLoadElim/uncomputable-backedge-taken-count.ll

diff --git a/llvm/test/Transforms/LoopLoadElim/uncomputable-backedge-taken-count.ll b/llvm/test/Transforms/LoopLoadElim/uncomputable-backedge-taken-count.ll
new file mode 100644
index 0000000..2dc1798
--- /dev/null
+++ b/llvm/test/Transforms/LoopLoadElim/uncomputable-backedge-taken-count.ll
@@ -0,0 +1,103 @@
+; RUN: opt -loop-load-elim -S < %s | FileCheck %s
+; RUN: opt -aa-pipeline=basic-aa -passes=loop-load-elim -S < %s | FileCheck %s
+
+target datalayout = "e-m:o-i32:64-f80:128-n8:16:32:64-S128"
+
+; TODO
+; Make sure loop-load-elimination triggers for a loop with uncomputable
+; backedge-taken counts when no runtime checks are required.
+define void @load_elim_no_runtime_checks(i32* noalias %A, i32* noalias %B, i32* noalias %C, i32 %N) {
+; CHECK-LABEL: load_elim_no_runtime_checks
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label %for.body
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %indvars.iv = phi i32 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+  %indvars.iv.next = add nuw nsw i32 %indvars.iv, 1
+
+  %Aidx_next = getelementptr inbounds i32, i32* %A, i32 %indvars.iv.next
+  %Bidx = getelementptr inbounds i32, i32* %B, i32 %indvars.iv
+  %Cidx = getelementptr inbounds i32, i32* %C, i32 %indvars.iv
+  %Aidx = getelementptr inbounds i32, i32* %A, i32 %indvars.iv
+
+  %b = load i32, i32* %Bidx, align 4
+  %a_p1 = add i32 %b, 2
+  store i32 %a_p1, i32* %Aidx_next, align 4
+
+  %a = load i32, i32* %Aidx, align 1
+  %c = mul i32 %a, 2
+  store i32 %c, i32* %Cidx, align 4
+
+  %exitcond = icmp eq i32 %indvars.iv.next, %a
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  ret void
+}
+
+; Make sure loop-load-elimination triggers for a loop with uncomputable
+; backedge-taken counts when no runtime checks are required.
+define void @load_elim_wrapping_runtime_checks(i32* noalias %A, i32* noalias %B, i32* noalias %C, i32 %N) {
+; CHECK-LABEL: @load_elim_wrapping_runtime_checks
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label %for.body
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %indvars.iv = phi i32 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+  %indvars.iv.next = add i32 %indvars.iv, 1
+
+  %Aidx_next = getelementptr inbounds i32, i32* %A, i32 %indvars.iv.next
+  %Bidx = getelementptr inbounds i32, i32* %B, i32 %indvars.iv
+  %Cidx = getelementptr inbounds i32, i32* %C, i32 %indvars.iv
+  %Aidx = getelementptr inbounds i32, i32* %A, i32 %indvars.iv
+
+  %b = load i32, i32* %Bidx, align 4
+  %a_p1 = add i32 %b, 2
+  store i32 %a_p1, i32* %Aidx_next, align 4
+
+  %a = load i32, i32* %Aidx, align 1
+  %c = mul i32 %a, 2
+  store i32 %c, i32* %Cidx, align 4
+
+  %exitcond = icmp eq i32 %indvars.iv.next, %a
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  ret void
+}
+
+; Make sure we do not crash when dealing with uncomputable backedge-taken counts
+; and a variable distance between accesses.
+define void @uncomputable_btc_crash(i8* %row, i32 %filter, i32* noalias %exits) local_unnamed_addr #0 {
+; CHECK-LABEL: @uncomputable_btc_crash
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    getelementptr
+; CHECK-NEXT:    br label %loop
+;
+entry:
+  %add.ptr = getelementptr inbounds i8, i8* %row, i32 %filter
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ]
+  %add.ptr.gep = getelementptr i8, i8* %add.ptr, i32 %iv
+  %row.gep = getelementptr i8, i8* %row, i32 %iv
+  %gep.1 = getelementptr i8, i8* %add.ptr.gep, i32 0
+  %gep.2 = getelementptr i8, i8* %row.gep, i32 0
+  %l = load i8, i8* %gep.2, align 1
+  store i8 %l, i8* %gep.1, align 1
+  %iv.next = add i32 %iv, 8
+  %exit.gep = getelementptr i32, i32* %exits, i32 %iv
+  %lv = load i32, i32* %exit.gep
+  %c = icmp eq i32 %lv, 120
+  br i1 %c, label %exit, label %loop
+
+exit:
+  ret void
+}
-- 
2.7.4