Revert max_by_val_size * 2

Author: Urgau

compiler/rustc_middle/src/ty/layout.rs

@@ -3362,11 +3362,9 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
 
                 match arg.layout.abi {
                     Abi::Aggregate { .. } => {
-                        // Pass and return structures up to 2 pointers in size by value,
-                        // matching `ScalarPair`. LLVM will usually pass these in 2 registers
-                        // which is more efficient than by-ref.
+                        // Pass and return structures up to 1 pointers in size by value.
                         let ptr_size = Pointer.size(self);
-                        let max_by_val_size = ptr_size * 2;
+                        let max_by_val_size = ptr_size;
                         let size = arg.layout.size;
 
                         if arg.layout.is_unsized() || size > max_by_val_size {

src/test/codegen/array-equality.rs

@@ -56,7 +56,8 @@ pub fn array_eq_zero_short(x: [u16; 3]) -> bool {
 #[no_mangle]
 pub fn array_eq_zero_mid(x: [u16; 8]) -> bool {
     // CHECK-NEXT: start:
-    // CHECK-NEXT: %[[EQ:.+]] = icmp eq i128 %0, 0
+    // CHECK: %[[LOAD:.+]] = load i128,
+    // CHECK-NEXT: %[[EQ:.+]] = icmp eq i128 %[[LOAD]], 0
     // CHECK-NEXT: ret i1 %[[EQ]]
     x == [0; 8]
 }

src/test/codegen/issue-37945.rs

@@ -17,7 +17,7 @@ pub fn is_empty_1(xs: Iter<f32>) -> bool {
 // CHECK-NEXT:  start:
 // CHECK-NEXT:    [[A:%.*]] = icmp ne {{i32\*|ptr}} %xs.1, null
 // CHECK-NEXT:    tail call void @llvm.assume(i1 [[A]])
-// CHECK-NEXT:    [[B:%.*]] = icmp eq {{i32\*|ptr}} %xs.1, %xs.0
+// CHECK-NEXT:    [[B:%.*]] = icmp eq {{i32\*|ptr}} {{%xs.1, %xs.0|%xs.0, %xs.1}}
 // CHECK-NEXT:    ret i1 [[B:%.*]]
     {xs}.next().is_none()
 }
@@ -28,7 +28,7 @@ pub fn is_empty_2(xs: Iter<f32>) -> bool {
 // CHECK-NEXT:  start:
 // CHECK-NEXT:    [[C:%.*]] = icmp ne {{i32\*|ptr}} %xs.1, null
 // CHECK-NEXT:    tail call void @llvm.assume(i1 [[C]])
-// CHECK-NEXT:    [[D:%.*]] = icmp eq {{i32\*|ptr}} %xs.1, %xs.0
+// CHECK-NEXT:    [[D:%.*]] = icmp eq {{i32\*|ptr}} {{%xs.1, %xs.0|%xs.0, %xs.1}}
 // CHECK-NEXT:    ret i1 [[D:%.*]]
     xs.map(|&x| x).next().is_none()
 }

src/test/codegen/union-abi.rs

@@ -65,7 +65,7 @@ pub fn test_UnionU128(_: UnionU128) -> UnionU128 { loop {} }
 
 #[repr(C)]
 pub union CUnionU128{a:u128}
-// CHECK: define void @test_CUnionU128(i128 %0)
+// CHECK: define void @test_CUnionU128({{%CUnionU128\*|ptr}} {{.*}} %_1)
 #[no_mangle]
 pub fn test_CUnionU128(_: CUnionU128) { loop {} }