[llvm] r366749 - [SimplifyCFG][NFC] Test that we fail to flatten CFG after forming @llvm.umul.with.overflow

[Roman Lebedev via llvm-commits]

Author: lebedevri
Date: Mon Jul 22 15:08:55 2019
New Revision: 366749

URL: http://llvm.org/viewvc/llvm-project?rev=366749&view=rev
Log:
[SimplifyCFG][NFC] Test that we fail to flatten CFG after forming @llvm.umul.with.overflow

Even if we formed @llvm.umul.with.overflow, we are still stuck
with that guard against div-by-zero, which is no longer needed,
because we didn't flatten the CFG.

Added:
    llvm/trunk/test/Transforms/SimplifyCFG/unsigned-multiplication-will-overflow.ll

Added: llvm/trunk/test/Transforms/SimplifyCFG/unsigned-multiplication-will-overflow.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/unsigned-multiplication-will-overflow.ll?rev=366749&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/unsigned-multiplication-will-overflow.ll (added)
+++ llvm/trunk/test/Transforms/SimplifyCFG/unsigned-multiplication-will-overflow.ll Mon Jul 22 15:08:55 2019
@@ -0,0 +1,38 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -simplifycfg -S | FileCheck %s
+
+; This is checking that the multiplication does overflow, with a leftover
+; guard against division-by-zero that was needed before InstCombine
+; produced llvm.umul.with.overflow.
+
+define i1 @will_overflow(i64 %size, i64 %nmemb) {
+; CHECK-LABEL: @will_overflow(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i64 [[SIZE:%.*]], 0
+; CHECK-NEXT:    br i1 [[CMP]], label [[LAND_END:%.*]], label [[LAND_RHS:%.*]]
+; CHECK:       land.rhs:
+; CHECK-NEXT:    [[UMUL:%.*]] = tail call { i64, i1 } @llvm.umul.with.overflow.i64(i64 [[SIZE]], i64 [[NMEMB:%.*]])
+; CHECK-NEXT:    [[UMUL_OV:%.*]] = extractvalue { i64, i1 } [[UMUL]], 1
+; CHECK-NEXT:    [[UMUL_NOT_OV:%.*]] = xor i1 [[UMUL_OV]], true
+; CHECK-NEXT:    br label [[LAND_END]]
+; CHECK:       land.end:
+; CHECK-NEXT:    [[TMP0:%.*]] = phi i1 [ true, [[ENTRY:%.*]] ], [ [[UMUL_NOT_OV]], [[LAND_RHS]] ]
+; CHECK-NEXT:    ret i1 [[TMP0]]
+;
+entry:
+  %cmp = icmp eq i64 %size, 0
+  br i1 %cmp, label %land.end, label %land.rhs
+
+land.rhs:                                         ; preds = %entry
+  %umul = tail call { i64, i1 } @llvm.umul.with.overflow.i64(i64 %size, i64 %nmemb)
+  %umul.ov = extractvalue { i64, i1 } %umul, 1
+  %umul.not.ov = xor i1 %umul.ov, true
+  br label %land.end
+
+land.end:                                         ; preds = %land.rhs, %entry
+  %0 = phi i1 [ true, %entry ], [ %umul.not.ov, %land.rhs ]
+  ret i1 %0
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare { i64, i1 } @llvm.umul.with.overflow.i64(i64, i64) #0