[NFC][CVP] Add tests where we can replace sext with zext

If the sign bit of the value that is being sign-extended is not set,
i.e. the value is non-negative (s>= 0), then zero-extension will suffice,
and is better for analysis: https://rise4fun.com/Alive/a8PD

llvm-svn: 374075

diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/sext.ll b/llvm/test/Transforms/CorrelatedValuePropagation/sext.ll
new file mode 100644 (file)
index 0000000..57227a0
--- /dev/null
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/sext.ll
@@ -0,0 +1,107 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -correlated-propagation -S | FileCheck %s
+
+; Check that debug locations are preserved. For more info see:
+;   https://llvm.org/docs/SourceLevelDebugging.html#fixing-errors
+; RUN: opt < %s -enable-debugify -correlated-propagation -S 2>&1 | \
+; RUN:   FileCheck %s -check-prefix=DEBUG
+; DEBUG: CheckModuleDebugify: PASS
+
+declare void @use64(i64)
+
+define void @test1(i32 %n) {
+; CHECK-LABEL: @test1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_COND:%.*]]
+; CHECK:       for.cond:
+; CHECK-NEXT:    [[A:%.*]] = phi i32 [ [[N:%.*]], [[ENTRY:%.*]] ], [ [[EXT:%.*]], [[FOR_BODY:%.*]] ]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[A]], 1
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[EXT_WIDE:%.*]] = sext i32 [[A]] to i64
+; CHECK-NEXT:    call void @use64(i64 [[EXT_WIDE]])
+; CHECK-NEXT:    [[EXT]] = trunc i64 [[EXT_WIDE]] to i32
+; CHECK-NEXT:    br label [[FOR_COND]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.body, %entry
+  %a = phi i32 [ %n, %entry ], [ %ext, %for.body ]
+  %cmp = icmp sgt i32 %a, 1
+  br i1 %cmp, label %for.body, label %for.end
+
+for.body:                                         ; preds = %for.cond
+  %ext.wide = sext i32 %a to i64
+  call void @use64(i64 %ext.wide)
+  %ext = trunc i64 %ext.wide to i32
+  br label %for.cond
+
+for.end:                                          ; preds = %for.cond
+  ret void
+}
+
+;; Negative test to show transform doesn't happen unless n > 0.
+define void @test2(i32 %n) {
+; CHECK-LABEL: @test2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_COND:%.*]]
+; CHECK:       for.cond:
+; CHECK-NEXT:    [[A:%.*]] = phi i32 [ [[N:%.*]], [[ENTRY:%.*]] ], [ [[EXT:%.*]], [[FOR_BODY:%.*]] ]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[A]], -2
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[EXT_WIDE:%.*]] = sext i32 [[A]] to i64
+; CHECK-NEXT:    call void @use64(i64 [[EXT_WIDE]])
+; CHECK-NEXT:    [[EXT]] = trunc i64 [[EXT_WIDE]] to i32
+; CHECK-NEXT:    br label [[FOR_COND]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.body, %entry
+  %a = phi i32 [ %n, %entry ], [ %ext, %for.body ]
+  %cmp = icmp sgt i32 %a, -2
+  br i1 %cmp, label %for.body, label %for.end
+
+for.body:                                         ; preds = %for.cond
+  %ext.wide = sext i32 %a to i64
+  call void @use64(i64 %ext.wide)
+  %ext = trunc i64 %ext.wide to i32
+  br label %for.cond
+
+for.end:                                          ; preds = %for.cond
+  ret void
+}
+
+;; Non looping test case.
+define void @test3(i32 %n) {
+; CHECK-LABEL: @test3(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[N:%.*]], 0
+; CHECK-NEXT:    br i1 [[CMP]], label [[BB:%.*]], label [[EXIT:%.*]]
+; CHECK:       bb:
+; CHECK-NEXT:    [[EXT_WIDE:%.*]] = sext i32 [[N]] to i64
+; CHECK-NEXT:    call void @use64(i64 [[EXT_WIDE]])
+; CHECK-NEXT:    [[EXT:%.*]] = trunc i64 [[EXT_WIDE]] to i32
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %cmp = icmp sgt i32 %n, 0
+  br i1 %cmp, label %bb, label %exit
+
+bb:
+  %ext.wide = sext i32 %n to i64
+  call void @use64(i64 %ext.wide)
+  %ext = trunc i64 %ext.wide to i32
+  br label %exit
+
+exit:
+  ret void
+}