Simplify codegen for niche-encoded variant tests

2 files changed, 26 insertions, 35 deletions

diff --git a/tests/codegen/enum/enum-discriminant-eq.rs b/tests/codegen/enum/enum-discriminant-eq.rs
index fd6f3499cb1..0494c5f551b 100644
--- a/tests/codegen/enum/enum-discriminant-eq.rs
+++ b/tests/codegen/enum/enum-discriminant-eq.rs
@@ -89,13 +89,13 @@ pub fn mid_bool_eq_discr(a: Mid<bool>, b: Mid<bool>) -> bool {
     // CHECK-LABEL: @mid_bool_eq_discr(
 
     // CHECK: %[[A_REL_DISCR:.+]] = add nsw i8 %a, -2
-    // CHECK: %[[A_IS_NICHE:.+]] = icmp ult i8 %[[A_REL_DISCR]], 3
+    // CHECK: %[[A_IS_NICHE:.+]] = icmp samesign ugt i8 %a, 1
     // CHECK: %[[A_NOT_HOLE:.+]] = icmp ne i8 %[[A_REL_DISCR]], 1
     // CHECK: tail call void @llvm.assume(i1 %[[A_NOT_HOLE]])
     // CHECK: %[[A_DISCR:.+]] = select i1 %[[A_IS_NICHE]], i8 %[[A_REL_DISCR]], i8 1
 
     // CHECK: %[[B_REL_DISCR:.+]] = add nsw i8 %b, -2
-    // CHECK: %[[B_IS_NICHE:.+]] = icmp ult i8 %[[B_REL_DISCR]], 3
+    // CHECK: %[[B_IS_NICHE:.+]] = icmp samesign ugt i8 %b, 1
     // CHECK: %[[B_NOT_HOLE:.+]] = icmp ne i8 %[[B_REL_DISCR]], 1
     // CHECK: tail call void @llvm.assume(i1 %[[B_NOT_HOLE]])
     // CHECK: %[[B_DISCR:.+]] = select i1 %[[B_IS_NICHE]], i8 %[[B_REL_DISCR]], i8 1
@@ -109,13 +109,13 @@ pub fn mid_ord_eq_discr(a: Mid<Ordering>, b: Mid<Ordering>) -> bool {
     // CHECK-LABEL: @mid_ord_eq_discr(
 
     // CHECK: %[[A_REL_DISCR:.+]] = add nsw i8 %a, -2
-    // CHECK: %[[A_IS_NICHE:.+]] = icmp ult i8 %[[A_REL_DISCR]], 3
+    // CHECK: %[[A_IS_NICHE:.+]] = icmp sgt i8 %a, 1
     // CHECK: %[[A_NOT_HOLE:.+]] = icmp ne i8 %[[A_REL_DISCR]], 1
     // CHECK: tail call void @llvm.assume(i1 %[[A_NOT_HOLE]])
     // CHECK: %[[A_DISCR:.+]] = select i1 %[[A_IS_NICHE]], i8 %[[A_REL_DISCR]], i8 1
 
     // CHECK: %[[B_REL_DISCR:.+]] = add nsw i8 %b, -2
-    // CHECK: %[[B_IS_NICHE:.+]] = icmp ult i8 %[[B_REL_DISCR]], 3
+    // CHECK: %[[B_IS_NICHE:.+]] = icmp sgt i8 %b, 1
     // CHECK: %[[B_NOT_HOLE:.+]] = icmp ne i8 %[[B_REL_DISCR]], 1
     // CHECK: tail call void @llvm.assume(i1 %[[B_NOT_HOLE]])
     // CHECK: %[[B_DISCR:.+]] = select i1 %[[B_IS_NICHE]], i8 %[[B_REL_DISCR]], i8 1
@@ -138,13 +138,13 @@ pub fn mid_ac_eq_discr(a: Mid<AC>, b: Mid<AC>) -> bool {
     // CHECK-LABEL: @mid_ac_eq_discr(
 
     // CHECK: %[[A_REL_DISCR:.+]] = xor i8 %a, -128
-    // CHECK: %[[A_IS_NICHE:.+]] = icmp ult i8 %[[A_REL_DISCR]], 3
+    // CHECK: %[[A_IS_NICHE:.+]] = icmp slt i8 %a, 0
     // CHECK: %[[A_NOT_HOLE:.+]] = icmp ne i8 %a, -127
     // CHECK: tail call void @llvm.assume(i1 %[[A_NOT_HOLE]])
     // CHECK: %[[A_DISCR:.+]] = select i1 %[[A_IS_NICHE]], i8 %[[A_REL_DISCR]], i8 1
 
     // CHECK: %[[B_REL_DISCR:.+]] = xor i8 %b, -128
-    // CHECK: %[[B_IS_NICHE:.+]] = icmp ult i8 %[[B_REL_DISCR]], 3
+    // CHECK: %[[B_IS_NICHE:.+]] = icmp slt i8 %b, 0
     // CHECK: %[[B_NOT_HOLE:.+]] = icmp ne i8 %b, -127
     // CHECK: tail call void @llvm.assume(i1 %[[B_NOT_HOLE]])
     // CHECK: %[[B_DISCR:.+]] = select i1 %[[B_IS_NICHE]], i8 %[[B_REL_DISCR]], i8 1
@@ -160,17 +160,17 @@ pub fn mid_ac_eq_discr(a: Mid<AC>, b: Mid<AC>) -> bool {
 pub fn mid_giant_eq_discr(a: Mid<Giant>, b: Mid<Giant>) -> bool {
     // CHECK-LABEL: @mid_giant_eq_discr(
 
-    // CHECK: %[[A_REL_DISCR_WIDE:.+]] = add nsw i128 %a, -5
-    // CHECK: %[[A_REL_DISCR:.+]] = trunc nsw i128 %[[A_REL_DISCR_WIDE]] to i64
-    // CHECK: %[[A_IS_NICHE:.+]] = icmp ult i128 %[[A_REL_DISCR_WIDE]], 3
-    // CHECK: %[[A_NOT_HOLE:.+]] = icmp ne i128 %[[A_REL_DISCR_WIDE]], 1
+    // CHECK: %[[A_TRUNC:.+]] = trunc nuw nsw i128 %a to i64
+    // CHECK: %[[A_REL_DISCR:.+]] = add nsw i64 %[[A_TRUNC]], -5
+    // CHECK: %[[A_IS_NICHE:.+]] = icmp samesign ugt i128 %a, 4
+    // CHECK: %[[A_NOT_HOLE:.+]] = icmp ne i64 %[[A_REL_DISCR]], 1
     // CHECK: tail call void @llvm.assume(i1 %[[A_NOT_HOLE]])
     // CHECK: %[[A_DISCR:.+]] = select i1 %[[A_IS_NICHE]], i64 %[[A_REL_DISCR]], i64 1
 
-    // CHECK: %[[B_REL_DISCR_WIDE:.+]] = add nsw i128 %b, -5
-    // CHECK: %[[B_REL_DISCR:.+]] = trunc nsw i128 %[[B_REL_DISCR_WIDE]] to i64
-    // CHECK: %[[B_IS_NICHE:.+]] = icmp ult i128 %[[B_REL_DISCR_WIDE]], 3
-    // CHECK: %[[B_NOT_HOLE:.+]] = icmp ne i128 %[[B_REL_DISCR_WIDE]], 1
+    // CHECK: %[[B_TRUNC:.+]] = trunc nuw nsw i128 %b to i64
+    // CHECK: %[[B_REL_DISCR:.+]] = add nsw i64 %[[B_TRUNC]], -5
+    // CHECK: %[[B_IS_NICHE:.+]] = icmp samesign ugt i128 %b, 4
+    // CHECK: %[[B_NOT_HOLE:.+]] = icmp ne i64 %[[B_REL_DISCR]], 1
     // CHECK: tail call void @llvm.assume(i1 %[[B_NOT_HOLE]])
     // CHECK: %[[B_DISCR:.+]] = select i1 %[[B_IS_NICHE]], i64 %[[B_REL_DISCR]], i64 1
 
@@ -181,14 +181,11 @@ pub fn mid_giant_eq_discr(a: Mid<Giant>, b: Mid<Giant>) -> bool {
 
 // In niche-encoded enums, testing for the untagged variant should optimize to a
 // straight-forward comparison looking for the natural range of the payload value.
-// FIXME: A bunch don't, though.
 
 #[unsafe(no_mangle)]
 pub fn mid_bool_is_thing(a: Mid<bool>) -> bool {
     // CHECK-LABEL: @mid_bool_is_thing(
-
-    // CHECK: %[[REL_DISCR:.+]] = add nsw i8 %a, -2
-    // CHECK: %[[R:.+]] = icmp ugt i8 %[[REL_DISCR]], 2
+    // CHECK: %[[R:.+]] = icmp samesign ult i8 %a, 2
     // CHECK: ret i1 %[[R]]
     discriminant_value(&a) == 1
 }
@@ -196,8 +193,7 @@ pub fn mid_bool_is_thing(a: Mid<bool>) -> bool {
 #[unsafe(no_mangle)]
 pub fn mid_ord_is_thing(a: Mid<Ordering>) -> bool {
     // CHECK-LABEL: @mid_ord_is_thing(
-    // CHECK: %[[REL_DISCR:.+]] = add nsw i8 %a, -2
-    // CHECK: %[[R:.+]] = icmp ugt i8 %[[REL_DISCR]], 2
+    // CHECK: %[[R:.+]] = icmp slt i8 %a, 2
     // CHECK: ret i1 %[[R]]
     discriminant_value(&a) == 1
 }
@@ -221,11 +217,7 @@ pub fn mid_ac_is_thing(a: Mid<AC>) -> bool {
 #[unsafe(no_mangle)]
 pub fn mid_giant_is_thing(a: Mid<Giant>) -> bool {
     // CHECK-LABEL: @mid_giant_is_thing(
-    // CHECK: %[[REL_DISCR_WIDE:.+]] = add nsw i128 %a, -5
-    // CHECK: %[[REL_DISCR:.+]] = trunc nsw i128 %[[REL_DISCR_WIDE]] to i64
-    // CHECK: %[[NOT_NICHE:.+]] = icmp ugt i128 %[[REL_DISCR_WIDE]], 2
-    // CHECK: %[[IS_MID_VARIANT:.+]] = icmp eq i64 %[[REL_DISCR]], 1
-    // CHECK: %[[R:.+]] = select i1 %[[NOT_NICHE]], i1 true, i1 %[[IS_MID_VARIANT]]
+    // CHECK: %[[R:.+]] = icmp samesign ult i128 %a, 5
     // CHECK: ret i1 %[[R]]
     discriminant_value(&a) == 1
 }
diff --git a/tests/codegen/enum/enum-match.rs b/tests/codegen/enum/enum-match.rs
index 9725e64def6..57db44ec74e 100644
--- a/tests/codegen/enum/enum-match.rs
+++ b/tests/codegen/enum/enum-match.rs
@@ -41,7 +41,7 @@ pub enum Enum1 {
 // CHECK-NEXT: start:
 // CHECK-NEXT: %[[REL_VAR:.+]] = add{{( nsw)?}} i8 %0, -2
 // CHECK-NEXT: %[[REL_VAR_WIDE:.+]] = zext i8 %[[REL_VAR]] to i64
-// CHECK-NEXT: %[[IS_NICHE:.+]] = icmp ult i8 %[[REL_VAR]], 2
+// CHECK-NEXT: %[[IS_NICHE:.+]] = icmp{{( samesign)?}} ugt i8 %0, 1
 // CHECK-NEXT: %[[NICHE_DISCR:.+]] = add nuw nsw i64 %[[REL_VAR_WIDE]], 1
 // CHECK-NEXT: %[[DISCR:.+]] = select i1 %[[IS_NICHE]], i64 %[[NICHE_DISCR]], i64 0
 // CHECK-NEXT: switch i64 %[[DISCR]]
@@ -148,10 +148,10 @@ pub enum MiddleNiche {
 // CHECK-LABEL: define{{( dso_local)?}} noundef{{( range\(i8 -?[0-9]+, -?[0-9]+\))?}} i8 @match4(i8{{.+}}%0)
 // CHECK-NEXT: start:
 // CHECK-NEXT: %[[REL_VAR:.+]] = add{{( nsw)?}} i8 %0, -2
-// CHECK-NEXT: %[[IS_NICHE:.+]] = icmp ult i8 %[[REL_VAR]], 5
 // CHECK-NEXT: %[[NOT_IMPOSSIBLE:.+]] = icmp ne i8 %[[REL_VAR]], 2
 // CHECK-NEXT: call void @llvm.assume(i1 %[[NOT_IMPOSSIBLE]])
-// CHECK-NEXT: %[[DISCR:.+]] = select i1 %[[IS_NICHE]], i8 %[[REL_VAR]], i8 2
+// CHECK-NEXT: %[[NOT_NICHE:.+]] = icmp{{( samesign)?}} ult i8 %0, 2
+// CHECK-NEXT: %[[DISCR:.+]] = select i1 %[[NOT_NICHE]], i8 2, i8 %[[REL_VAR]]
 // CHECK-NEXT: switch i8 %[[DISCR]]
 #[no_mangle]
 pub fn match4(e: MiddleNiche) -> u8 {
@@ -167,11 +167,10 @@ pub fn match4(e: MiddleNiche) -> u8 {
 
 // CHECK-LABEL: define{{.+}}i1 @match4_is_c(i8{{.+}}%e)
 // CHECK-NEXT: start
-// CHECK-NEXT: %[[REL_VAR:.+]] = add{{( nsw)?}} i8 %e, -2
-// CHECK-NEXT: %[[NOT_NICHE:.+]] = icmp ugt i8 %[[REL_VAR]], 4
-// CHECK-NEXT: %[[NOT_IMPOSSIBLE:.+]] = icmp ne i8 %[[REL_VAR]], 2
+// CHECK-NEXT: %[[NOT_IMPOSSIBLE:.+]] = icmp ne i8 %e, 4
 // CHECK-NEXT: call void @llvm.assume(i1 %[[NOT_IMPOSSIBLE]])
-// CHECK-NEXT: ret i1 %[[NOT_NICHE]]
+// CHECK-NEXT: %[[IS_C:.+]] = icmp{{( samesign)?}} ult i8 %e, 2
+// CHECK-NEXT: ret i1 %[[IS_C]]
 #[no_mangle]
 pub fn match4_is_c(e: MiddleNiche) -> bool {
     // Before #139098, this couldn't optimize out the `select` because it looked
@@ -453,10 +452,10 @@ pub enum HugeVariantIndex {
 // CHECK-NEXT: start:
 // CHECK-NEXT: %[[REL_VAR:.+]] = add{{( nsw)?}} i8 %0, -2
 // CHECK-NEXT: %[[REL_VAR_WIDE:.+]] = zext i8 %[[REL_VAR]] to i64
-// CHECK-NEXT: %[[IS_NICHE:.+]] = icmp ult i8 %[[REL_VAR]], 3
-// CHECK-NEXT: %[[NOT_IMPOSSIBLE:.+]] = icmp ne i8 %[[REL_VAR]], 1
-// CHECK-NEXT: call void @llvm.assume(i1 %[[NOT_IMPOSSIBLE]])
+// CHECK-NEXT: %[[IS_NICHE:.+]] = icmp{{( samesign)?}} ugt i8 %0, 1
 // CHECK-NEXT: %[[NICHE_DISCR:.+]] = add nuw nsw i64 %[[REL_VAR_WIDE]], 257
+// CHECK-NEXT: %[[NOT_IMPOSSIBLE:.+]] = icmp ne i64 %[[NICHE_DISCR]], 258
+// CHECK-NEXT: call void @llvm.assume(i1 %[[NOT_IMPOSSIBLE]])
 // CHECK-NEXT: %[[DISCR:.+]] = select i1 %[[IS_NICHE]], i64 %[[NICHE_DISCR]], i64 258
 // CHECK-NEXT: switch i64 %[[DISCR]],
 // CHECK-NEXT:   i64 257,