[JumpThreading] Add a test for D84944 ; NFC

Author: aqjune

llvm/test/Transforms/JumpThreading/pre-load.ll

@@ -0,0 +1,84 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -jump-threading -S < %s | FileCheck %s
+
+@x = global i32 0
+@y = global i32 0
+
+declare void @f()
+declare void @g()
+
+define i32 @pre(i1 %cond, i32 %n) {
+; CHECK-LABEL: @pre(
+; CHECK-NEXT:    br i1 [[COND:%.*]], label [[C_THREAD:%.*]], label [[C:%.*]]
+; CHECK:       C.thread:
+; CHECK-NEXT:    store i32 0, i32* @x, align 4
+; CHECK-NEXT:    br label [[YES:%.*]]
+; CHECK:       C:
+; CHECK-NEXT:    [[A_PR:%.*]] = load i32, i32* @y, align 4
+; CHECK-NEXT:    [[COND2:%.*]] = icmp eq i32 [[A_PR]], 0
+; CHECK-NEXT:    br i1 [[COND2]], label [[YES]], label [[NO:%.*]]
+; CHECK:       YES:
+; CHECK-NEXT:    [[A4:%.*]] = phi i32 [ 0, [[C_THREAD]] ], [ [[A_PR]], [[C]] ]
+; CHECK-NEXT:    call void @f()
+; CHECK-NEXT:    ret i32 [[A4]]
+; CHECK:       NO:
+; CHECK-NEXT:    call void @g()
+; CHECK-NEXT:    ret i32 1
+;
+  br i1 %cond, label %A, label %B
+A:
+  store i32 0, i32* @x
+  br label %C
+B:
+  br label %C
+C:
+  %ptr = phi i32* [@x, %A], [@y, %B]
+  %a = load i32, i32* %ptr
+  %cond2 = icmp eq i32 %a, 0
+  br i1 %cond2, label %YES, label %NO
+YES:
+  call void @f()
+  ret i32 %a
+NO:
+  call void @g()
+  ret i32 1
+}
+
+define i32 @pre_freeze(i1 %cond, i32 %n) {
+; CHECK-LABEL: @pre_freeze(
+; CHECK-NEXT:    br i1 [[COND:%.*]], label [[A:%.*]], label [[C:%.*]]
+; CHECK:       A:
+; CHECK-NEXT:    store i32 0, i32* @x, align 4
+; CHECK-NEXT:    br label [[C]]
+; CHECK:       C:
+; CHECK-NEXT:    [[PTR:%.*]] = phi i32* [ @x, [[A]] ], [ @y, [[TMP0:%.*]] ]
+; CHECK-NEXT:    [[A:%.*]] = load i32, i32* [[PTR]], align 4
+; CHECK-NEXT:    [[COND2:%.*]] = icmp eq i32 [[A]], 0
+; CHECK-NEXT:    [[COND2_FR:%.*]] = freeze i1 [[COND2]]
+; CHECK-NEXT:    br i1 [[COND2_FR]], label [[YES:%.*]], label [[NO:%.*]]
+; CHECK:       YES:
+; CHECK-NEXT:    call void @f()
+; CHECK-NEXT:    ret i32 [[A]]
+; CHECK:       NO:
+; CHECK-NEXT:    call void @g()
+; CHECK-NEXT:    ret i32 1
+;
+  br i1 %cond, label %A, label %B
+A:
+  store i32 0, i32* @x
+  br label %C
+B:
+  br label %C
+C:
+  %ptr = phi i32* [@x, %A], [@y, %B]
+  %a = load i32, i32* %ptr
+  %cond2 = icmp eq i32 %a, 0
+  %cond2.fr = freeze i1 %cond2
+  br i1 %cond2.fr, label %YES, label %NO
+YES:
+  call void @f()
+  ret i32 %a
+NO:
+  call void @g()
+  ret i32 1
+}