[InstCombine] don't assert that division-by-constant has been folded (PR30281)

This is effectively a revert of:
https://reviews.llvm.org/rL280115

And this should fix
https://llvm.org/bugs/show_bug.cgi?id=30281:

llvm-svn: 280677

1 files changed, 93 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/icmp-div-constant.ll b/llvm/test/Transforms/InstCombine/icmp-div-constant.ll
new file mode 100644
index 00000000000..98900ef8113
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/icmp-div-constant.ll
@@ -0,0 +1,93 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; PR30281 - https://llvm.org/bugs/show_bug.cgi?id=30281
+
+; All of these tests contain foldable division-by-constant instructions, but we
+; can't assert that those folds have occurred before we process the later icmp.
+
+define i32 @icmp_div(i16 %a, i16 %c) {
+; CHECK-LABEL: @icmp_div(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i16 %a, 0
+; CHECK-NEXT:    br i1 [[TOBOOL]], label %then, label %exit
+; CHECK:       then:
+; CHECK-NEXT:    [[NOT_CMP:%.*]] = icmp eq i16 %c, 0
+; CHECK-NEXT:    [[PHITMP1:%.*]] = sext i1 [[NOT_CMP]] to i32
+; CHECK-NEXT:    br label %exit
+; CHECK:       exit:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i32 [ -1, %entry ], [ [[PHI:%.*]]tmp1, %then ]
+; CHECK-NEXT:    ret i32 [[PHI]]
+;
+entry:
+  %tobool = icmp eq i16 %a, 0
+  br i1 %tobool, label %then, label %exit
+
+then:
+  %div = sdiv i16 %c, -1
+  %cmp = icmp ne i16 %div, 0
+  br label %exit
+
+exit:
+  %phi = phi i1 [ false, %entry ], [ %cmp, %then ]
+  %zext = zext i1 %phi to i32
+  %add = add nsw i32 %zext, -1
+  ret i32 %add
+}
+
+define i32 @icmp_div2(i16 %a, i16 %c) {
+; CHECK-LABEL: @icmp_div2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i16 %a, 0
+; CHECK-NEXT:    br i1 [[TOBOOL]], label %then, label %exit
+; CHECK:       then:
+; CHECK-NEXT:    br label %exit
+; CHECK:       exit:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i32 [ -1, %entry ], [ 0, %then ]
+; CHECK-NEXT:    ret i32 [[PHI]]
+;
+entry:
+  %tobool = icmp eq i16 %a, 0
+  br i1 %tobool, label %then, label %exit
+
+then:
+  %div = sdiv i16 %c, 0
+  %cmp = icmp ne i16 %div, 0
+  br label %exit
+
+exit:
+  %phi = phi i1 [ false, %entry ], [ %cmp, %then ]
+  %zext = zext i1 %phi to i32
+  %add = add nsw i32 %zext, -1
+  ret i32 %add
+}
+
+define i32 @icmp_div3(i16 %a, i16 %c) {
+; CHECK-LABEL: @icmp_div3(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i16 %a, 0
+; CHECK-NEXT:    br i1 [[TOBOOL]], label %then, label %exit
+; CHECK:       then:
+; CHECK-NEXT:    [[NOT_CMP:%.*]] = icmp eq i16 %c, 0
+; CHECK-NEXT:    [[PHITMP1:%.*]] = sext i1 [[NOT_CMP]] to i32
+; CHECK-NEXT:    br label %exit
+; CHECK:       exit:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i32 [ -1, %entry ], [ [[PHI:%.*]]tmp1, %then ]
+; CHECK-NEXT:    ret i32 [[PHI]]
+;
+entry:
+  %tobool = icmp eq i16 %a, 0
+  br i1 %tobool, label %then, label %exit
+
+then:
+  %div = sdiv i16 %c, 1
+  %cmp = icmp ne i16 %div, 0
+  br label %exit
+
+exit:
+  %phi = phi i1 [ false, %entry ], [ %cmp, %then ]
+  %zext = zext i1 %phi to i32
+  %add = add nsw i32 %zext, -1
+  ret i32 %add
+}
+