[llvm] r362159 - [NFC][ARM] Add a test that potentially causes endless combine loop with D62266

[Roman Lebedev via llvm-commits]

Author: lebedevri
Date: Thu May 30 14:41:21 2019
New Revision: 362159

URL: http://llvm.org/viewvc/llvm-project?rev=362159&view=rev
Log:
[NFC][ARM] Add a test that potentially causes endless combine loop with D62266

Added:
    llvm/trunk/test/CodeGen/ARM/sub-from-const-hoisting.ll

Added: llvm/trunk/test/CodeGen/ARM/sub-from-const-hoisting.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/sub-from-const-hoisting.ll?rev=362159&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/sub-from-const-hoisting.ll (added)
+++ llvm/trunk/test/CodeGen/ARM/sub-from-const-hoisting.ll Thu May 30 14:41:21 2019
@@ -0,0 +1,60 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv6m-arm-none-eabi"
+
+; From https://reviews.llvm.org/D62266
+; This used to cause an endless loop in DAGCombine,
+; since we were hoisting two binops with constants, one constant being opaque,
+; which is why they weren't getting constant folded.
+
+ at a = dso_local local_unnamed_addr global i32 0, align 4
+ at b = dso_local local_unnamed_addr global i32 0, align 4
+
+; Function Attrs: minsize nounwind optsize
+define dso_local i32 @c() local_unnamed_addr #0 {
+; CHECK-LABEL: c:
+; CHECK:       @ %bb.0: @ %entry
+; CHECK-NEXT:    .save {r4, lr}
+; CHECK-NEXT:    push {r4, lr}
+; CHECK-NEXT:    ldr r0, .LCPI0_0
+; CHECK-NEXT:    ldr r0, [r0]
+; CHECK-NEXT:    ldr r4, .LCPI0_1
+; CHECK-NEXT:    subs r0, r4, r0
+; CHECK-NEXT:    adds r0, r0, #1
+; CHECK-NEXT:    bl d
+; CHECK-NEXT:    ldr r0, .LCPI0_2
+; CHECK-NEXT:    ldr r0, [r0]
+; CHECK-NEXT:    cmp r0, r4
+; CHECK-NEXT:    ble .LBB0_2
+; CHECK-NEXT:  @ %bb.1: @ %if.then
+; CHECK-NEXT:    bl e
+; CHECK-NEXT:  .LBB0_2: @ %if.end
+; CHECK-NEXT:    pop {r4, pc}
+; CHECK-NEXT:    .p2align 2
+; CHECK-NEXT:  @ %bb.3:
+; CHECK-NEXT:  .LCPI0_0:
+; CHECK-NEXT:    .long a
+; CHECK-NEXT:  .LCPI0_1:
+; CHECK-NEXT:    .long 1999 @ 0x7cf
+; CHECK-NEXT:  .LCPI0_2:
+; CHECK-NEXT:    .long b
+entry:
+  %0 = load i32, i32* @a, align 4
+  %sub = sub nsw i32 2000, %0
+  %call = tail call i32 bitcast (i32 (...)* @d to i32 (i32)*)(i32 %sub) #2
+  %1 = load i32, i32* @b, align 4
+  %cmp = icmp sgt i32 %1, 1999
+  br i1 %cmp, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  %call1 = tail call i32 bitcast (i32 (...)* @e to i32 ()*)() #2
+  br label %if.end
+
+if.end:                                           ; preds = %if.then, %entry
+  ret i32 undef
+}
+
+declare dso_local i32 @d(...) local_unnamed_addr #1
+declare dso_local i32 @e(...) local_unnamed_addr #1