Imported Upstream version 5.18.0.161

Former-commit-id: 4db48158d3a35497b8f118ab21b5f08ac3d86d98

external/llvm/test/Transforms/EarlyCSE/conditional.ll

@@ -0,0 +1,108 @@
+; RUN: opt -early-cse -S < %s | FileCheck %s
+; RUN: opt -basicaa -early-cse-memssa -S < %s | FileCheck %s
+
+; Can we CSE a known condition to a constant?
+define i1 @test(i8* %p) {
+; CHECK-LABEL: @test
+entry:
+  %cnd1 = icmp eq i8* %p, null
+  br i1 %cnd1, label %taken, label %untaken
+
+taken:
+; CHECK-LABEL: taken:
+; CHECK-NEXT: ret i1 true
+  %cnd2 = icmp eq i8* %p, null
+  ret i1 %cnd2
+
+untaken:
+; CHECK-LABEL: untaken:
+; CHECK-NEXT: ret i1 false
+  %cnd3 = icmp eq i8* %p, null
+  ret i1 %cnd3
+}
+
+; We can CSE the condition, but we *don't* know it's value after the merge
+define i1 @test_neg1(i8* %p) {
+; CHECK-LABEL: @test_neg1
+entry:
+  %cnd1 = icmp eq i8* %p, null
+  br i1 %cnd1, label %taken, label %untaken
+
+taken:
+  br label %merge
+
+untaken:
+  br label %merge
+
+merge:
+; CHECK-LABEL: merge:
+; CHECK-NEXT: ret i1 %cnd1
+  %cnd3 = icmp eq i8* %p, null
+  ret i1 %cnd3
+}
+
+; Check specifically for a case where we have a unique predecessor, but
+; not a single predecessor.  We can not know the value of the condition here.
+define i1 @test_neg2(i8* %p) {
+; CHECK-LABEL: @test_neg2
+entry:
+  %cnd1 = icmp eq i8* %p, null
+  br i1 %cnd1, label %merge, label %merge
+
+merge:
+; CHECK-LABEL: merge:
+; CHECK-NEXT: ret i1 %cnd1
+  %cnd3 = icmp eq i8* %p, null
+  ret i1 %cnd3
+}
+
+; Replace a use rather than CSE
+define i1 @test2(i8* %p) {
+; CHECK-LABEL: @test2
+entry:
+  %cnd = icmp eq i8* %p, null
+  br i1 %cnd, label %taken, label %untaken
+
+taken:
+; CHECK-LABEL: taken:
+; CHECK-NEXT: ret i1 true
+  ret i1 %cnd
+
+untaken:
+; CHECK-LABEL: untaken:
+; CHECK-NEXT: ret i1 false
+  ret i1 %cnd
+}
+
+; Not legal to replace use given it's not dominated by edge
+define i1 @test2_neg1(i8* %p) {
+; CHECK-LABEL: @test2_neg1
+entry:
+  %cnd1 = icmp eq i8* %p, null
+  br i1 %cnd1, label %taken, label %untaken
+
+taken:
+  br label %merge
+
+untaken:
+  br label %merge
+
+merge:
+; CHECK-LABEL: merge:
+; CHECK-NEXT: ret i1 %cnd1
+  ret i1 %cnd1
+}
+
+; Another single predecessor test, but for dominated use
+define i1 @test2_neg2(i8* %p) {
+; CHECK-LABEL: @test2_neg2
+entry:
+  %cnd1 = icmp eq i8* %p, null
+  br i1 %cnd1, label %merge, label %merge
+
+merge:
+; CHECK-LABEL: merge:
+; CHECK-NEXT: ret i1 %cnd1
+  ret i1 %cnd1
+}
+