[CGP] Additional tests for removing operand of assume. NFC.

Author: Serguei Katkov

llvm/test/Transforms/CodeGenPrepare/X86/delete-assume-dead-code.ll

@@ -49,7 +49,7 @@ header:
   %iv.inc = add i32 %iv, 1
   %iv2.inc = add i32 %iv2, 1
   %cmp = icmp eq i32 %iv, %N
-  %cmp2 = icmp slt i32 %iv2, %N
+  %cmp2 = icmp sle i32 %iv2, %N
   call void @llvm.assume(i1 %cmp2)
   br i1 %cmp, label %exit, label %header
 
@@ -80,13 +80,83 @@ header:
   %iv.inc = add i32 %iv, 1
   %iv2.inc = add i32 %iv2, 1
   %cmp = icmp eq i32 %iv, %N
-  %cmp2 = icmp slt i32 %iv2.inc, %N
+  %cmp2 = icmp sle i32 %iv2.inc, %N
   call void @llvm.assume(i1 %cmp2)
   br i1 %cmp, label %exit, label %header
 
 exit:
   ret i32 %iv
 }
 
+; Two assumes case.
+define i32 @test4(i32 %N) nounwind {
+; CHECK-LABEL: @test4(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[HEADER:%.*]]
+; CHECK:       header:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_INC:%.*]], [[HEADER]] ]
+; CHECK-NEXT:    [[IV2:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[IV2_INC:%.*]], [[HEADER]] ]
+; CHECK-NEXT:    [[IV_INC]] = add i32 [[IV]], 1
+; CHECK-NEXT:    [[IV2_INC]] = add i32 [[IV2]], 1
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[IV]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[EXIT:%.*]], label [[HEADER]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret i32 [[IV]]
+;
+entry:
+  br label %header
+
+header:
+  %iv = phi i32 [0, %entry], [%iv.inc, %header]
+  %iv2 = phi i32 [0, %entry], [%iv2.inc, %header]
+  %iv.inc = add i32 %iv, 1
+  %iv2.inc = add i32 %iv2, 1
+  %cmp = icmp eq i32 %iv, %N
+  %cmp2 = icmp sle i32 %iv2.inc, %N
+  call void @llvm.assume(i1 %cmp2)
+  %cmp3 = icmp sge i32 %iv2.inc, 0
+  call void @llvm.assume(i1 %cmp3)
+  br i1 %cmp, label %exit, label %header
+
+exit:
+  ret i32 %iv
+}
+
+; phi is used in assume and in compare.
+define i32 @test5(i32 %N, i32 %M) nounwind {
+; CHECK-LABEL: @test5(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[HEADER:%.*]]
+; CHECK:       header:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_INC:%.*]], [[HEADER]] ]
+; CHECK-NEXT:    [[IV2:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[IV2_INC:%.*]], [[HEADER]] ]
+; CHECK-NEXT:    [[IV_INC]] = add i32 [[IV]], 1
+; CHECK-NEXT:    [[IV2_INC]] = add i32 [[IV2]], 1
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[IV]], [[N:%.*]]
+; CHECK-NEXT:    [[CMP3:%.*]] = icmp sge i32 [[IV2_INC]], [[M:%.*]]
+; CHECK-NEXT:    [[CMP4:%.*]] = and i1 [[CMP]], [[CMP3]]
+; CHECK-NEXT:    br i1 [[CMP4]], label [[EXIT:%.*]], label [[HEADER]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret i32 [[IV]]
+;
+entry:
+  br label %header
+
+header:
+  %iv = phi i32 [0, %entry], [%iv.inc, %header]
+  %iv2 = phi i32 [0, %entry], [%iv2.inc, %header]
+  %iv.inc = add i32 %iv, 1
+  %iv2.inc = add i32 %iv2, 1
+  %cmp = icmp eq i32 %iv, %N
+  %cmp2 = icmp sle i32 %iv2.inc, %N
+  call void @llvm.assume(i1 %cmp2)
+  %cmp3 = icmp sge i32 %iv2.inc, %M
+  %cmp4 = and i1 %cmp, %cmp3
+  br i1 %cmp4, label %exit, label %header
+
+exit:
+  ret i32 %iv
+}
+
 declare i64 @foo(ptr) nounwind readonly willreturn
 declare void @llvm.assume(i1 noundef) nounwind willreturn