Do not intern too large aggregates.

cjgillot · cjgillot · commit 87104ba5b3d3 · 2023-09-23T15:07:53.000Z
diff --git a/compiler/rustc_mir_transform/src/gvn.rs b/compiler/rustc_mir_transform/src/gvn.rs
@@ -284,24 +284,30 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
                     .collect::<Option<Vec<_>>>()?;
                 let variant = if ty.is_enum() { Some(variant) } else { None };
                 let ty = self.ecx.layout_of(ty).ok()?;
-                let alloc_id = self
-                    .ecx
-                    .intern_with_temp_alloc(ty, |ecx, dest| {
-                        let variant_dest = if let Some(variant) = variant {
-                            ecx.project_downcast(dest, variant)?
-                        } else {
-                            dest.clone()
-                        };
-                        for (field_index, op) in fields.into_iter().enumerate() {
-                            let field_dest = ecx.project_field(&variant_dest, field_index)?;
-                            ecx.copy_op(op, &field_dest, /*allow_transmute*/ false)?;
-                        }
-                        ecx.write_discriminant(variant.unwrap_or(FIRST_VARIANT), dest)
-                    })
-                    .ok()?;
-                let mplace =
-                    self.ecx.raw_const_to_mplace(ConstAlloc { alloc_id, ty: ty.ty }).ok()?;
-                mplace.into()
+                if ty.is_zst() {
+                    ImmTy::uninit(ty).into()
+                } else if matches!(ty.abi, Abi::Scalar(..) | Abi::ScalarPair(..)) {
+                    let alloc_id = self
+                        .ecx
+                        .intern_with_temp_alloc(ty, |ecx, dest| {
+                            let variant_dest = if let Some(variant) = variant {
+                                ecx.project_downcast(dest, variant)?
+                            } else {
+                                dest.clone()
+                            };
+                            for (field_index, op) in fields.into_iter().enumerate() {
+                                let field_dest = ecx.project_field(&variant_dest, field_index)?;
+                                ecx.copy_op(op, &field_dest, /*allow_transmute*/ false)?;
+                            }
+                            ecx.write_discriminant(variant.unwrap_or(FIRST_VARIANT), dest)
+                        })
+                        .ok()?;
+                    let mplace =
+                        self.ecx.raw_const_to_mplace(ConstAlloc { alloc_id, ty: ty.ty }).ok()?;
+                    mplace.into()
+                } else {
+                    return None;
+                }
             }
 
             Projection(base, elem) => {
diff --git a/tests/mir-opt/const_prop/aggregate.main.GVN.panic-abort.diff b/tests/mir-opt/const_prop/aggregate.main.GVN.panic-abort.diff
@@ -18,18 +18,15 @@
           StorageLive(_2);
           StorageLive(_3);
           _3 = (const 0_i32, const 1_u8, const 2_i32);
--         _2 = (_3.1: u8);
--         _1 = Add(move _2, const 0_u8);
-+         _2 = const 1_u8;
-+         _1 = const 1_u8;
+          _2 = (_3.1: u8);
+          _1 = Add(move _2, const 0_u8);
           StorageDead(_2);
           StorageDead(_3);
           StorageLive(_4);
           StorageLive(_5);
--         _5 = _1;
+          _5 = _1;
 -         _4 = foo(move _5) -> [return: bb1, unwind unreachable];
-+         _5 = const 1_u8;
-+         _4 = foo(const 1_u8) -> [return: bb1, unwind unreachable];
++         _4 = foo(_1) -> [return: bb1, unwind unreachable];
       }
   
       bb1: {
diff --git a/tests/mir-opt/const_prop/aggregate.main.GVN.panic-unwind.diff b/tests/mir-opt/const_prop/aggregate.main.GVN.panic-unwind.diff
@@ -18,18 +18,15 @@
           StorageLive(_2);
           StorageLive(_3);
           _3 = (const 0_i32, const 1_u8, const 2_i32);
--         _2 = (_3.1: u8);
--         _1 = Add(move _2, const 0_u8);
-+         _2 = const 1_u8;
-+         _1 = const 1_u8;
+          _2 = (_3.1: u8);
+          _1 = Add(move _2, const 0_u8);
           StorageDead(_2);
           StorageDead(_3);
           StorageLive(_4);
           StorageLive(_5);
--         _5 = _1;
+          _5 = _1;
 -         _4 = foo(move _5) -> [return: bb1, unwind continue];
-+         _5 = const 1_u8;
-+         _4 = foo(const 1_u8) -> [return: bb1, unwind continue];
++         _4 = foo(_1) -> [return: bb1, unwind continue];
       }
   
       bb1: {
diff --git a/tests/mir-opt/const_prop/aggregate.main.PreCodegen.after.panic-abort.mir b/tests/mir-opt/const_prop/aggregate.main.PreCodegen.after.panic-abort.mir
@@ -16,14 +16,14 @@ fn main() -> () {
         StorageLive(_2);
         StorageLive(_3);
         _3 = (const 0_i32, const 1_u8, const 2_i32);
-        _2 = const 1_u8;
-        _1 = const 1_u8;
+        _2 = (_3.1: u8);
+        _1 = Add(move _2, const 0_u8);
         StorageDead(_2);
         StorageDead(_3);
         StorageLive(_4);
         StorageLive(_5);
-        _5 = const 1_u8;
-        _4 = foo(const 1_u8) -> [return: bb1, unwind unreachable];
+        _5 = _1;
+        _4 = foo(_1) -> [return: bb1, unwind unreachable];
     }
 
     bb1: {
diff --git a/tests/mir-opt/const_prop/aggregate.main.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/const_prop/aggregate.main.PreCodegen.after.panic-unwind.mir
@@ -16,14 +16,14 @@ fn main() -> () {
         StorageLive(_2);
         StorageLive(_3);
         _3 = (const 0_i32, const 1_u8, const 2_i32);
-        _2 = const 1_u8;
-        _1 = const 1_u8;
+        _2 = (_3.1: u8);
+        _1 = Add(move _2, const 0_u8);
         StorageDead(_2);
         StorageDead(_3);
         StorageLive(_4);
         StorageLive(_5);
-        _5 = const 1_u8;
-        _4 = foo(const 1_u8) -> [return: bb1, unwind continue];
+        _5 = _1;
+        _4 = foo(_1) -> [return: bb1, unwind continue];
     }
 
     bb1: {
diff --git a/tests/mir-opt/const_prop/array_index.main.GVN.32bit.panic-abort.diff b/tests/mir-opt/const_prop/array_index.main.GVN.32bit.panic-abort.diff
@@ -18,12 +18,11 @@
           _2 = [const 0_u32, const 1_u32, const 2_u32, const 3_u32];
           StorageLive(_3);
           _3 = const 2_usize;
--         _4 = Len(_2);
+          _4 = Len(_2);
 -         _5 = Lt(_3, _4);
 -         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind unreachable];
-+         _4 = const 4_usize;
-+         _5 = const true;
-+         assert(const true, "index out of bounds: the length is {} but the index is {}", const 4_usize, const 2_usize) -> [success: bb1, unwind unreachable];
++         _5 = Lt(const 2_usize, _4);
++         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind unreachable];
       }
   
       bb1: {
diff --git a/tests/mir-opt/const_prop/array_index.main.GVN.32bit.panic-unwind.diff b/tests/mir-opt/const_prop/array_index.main.GVN.32bit.panic-unwind.diff
@@ -18,12 +18,11 @@
           _2 = [const 0_u32, const 1_u32, const 2_u32, const 3_u32];
           StorageLive(_3);
           _3 = const 2_usize;
--         _4 = Len(_2);
+          _4 = Len(_2);
 -         _5 = Lt(_3, _4);
 -         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind continue];
-+         _4 = const 4_usize;
-+         _5 = const true;
-+         assert(const true, "index out of bounds: the length is {} but the index is {}", const 4_usize, const 2_usize) -> [success: bb1, unwind continue];
++         _5 = Lt(const 2_usize, _4);
++         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind continue];
       }
   
       bb1: {
diff --git a/tests/mir-opt/const_prop/array_index.main.GVN.64bit.panic-unwind.diff b/tests/mir-opt/const_prop/array_index.main.GVN.64bit.panic-unwind.diff
@@ -18,12 +18,11 @@
           _2 = [const 0_u32, const 1_u32, const 2_u32, const 3_u32];
           StorageLive(_3);
           _3 = const 2_usize;
--         _4 = Len(_2);
+          _4 = Len(_2);
 -         _5 = Lt(_3, _4);
 -         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> [success: bb1, unwind continue];
-+         _4 = const 4_usize;
-+         _5 = const true;
-+         assert(const true, "index out of bounds: the length is {} but the index is {}", const 4_usize, const 2_usize) -> [success: bb1, unwind continue];
++         _5 = Lt(const 2_usize, _4);
++         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, const 2_usize) -> [success: bb1, unwind continue];
       }
   
       bb1: {
diff --git a/tests/mir-opt/pre-codegen/optimizes_into_variable.main.GVN.32bit.panic-abort.diff b/tests/mir-opt/pre-codegen/optimizes_into_variable.main.GVN.32bit.panic-abort.diff
@@ -56,7 +56,7 @@
       }
 + }
 + 
-+ alloc5 (size: 8, align: 4) {
++ alloc4 (size: 8, align: 4) {
 +     04 00 00 00 00 __ __ __                         │ .....░░░
   }
   
diff --git a/tests/mir-opt/pre-codegen/optimizes_into_variable.main.GVN.32bit.panic-unwind.diff b/tests/mir-opt/pre-codegen/optimizes_into_variable.main.GVN.32bit.panic-unwind.diff
@@ -56,7 +56,7 @@
       }
 + }
 + 
-+ alloc5 (size: 8, align: 4) {
++ alloc4 (size: 8, align: 4) {
 +     04 00 00 00 00 __ __ __                         │ .....░░░
   }
   
diff --git a/tests/mir-opt/pre-codegen/optimizes_into_variable.main.GVN.64bit.panic-unwind.diff b/tests/mir-opt/pre-codegen/optimizes_into_variable.main.GVN.64bit.panic-unwind.diff
@@ -56,7 +56,7 @@
       }
 + }
 + 
-+ alloc5 (size: 8, align: 4) {
++ alloc4 (size: 8, align: 4) {
 +     04 00 00 00 00 __ __ __                         │ .....░░░
   }
   
diff --git a/tests/mir-opt/pre-codegen/simple_option_map.ezmap.PreCodegen.after.mir b/tests/mir-opt/pre-codegen/simple_option_map.ezmap.PreCodegen.after.mir
@@ -45,6 +45,6 @@ fn ezmap(_1: Option<i32>) -> Option<i32> {
     }
 }
 
-alloc14 (size: 8, align: 4) {
+alloc13 (size: 8, align: 4) {
     00 00 00 00 __ __ __ __                         │ ....░░░░
 }

Original file line number	Diff line number	Diff line change
`@@ -56,7 +56,7 @@`
`56`	`56`	`}`
`57`	`57`	`+ }`
`58`	`58`	`+`
`59`		`-+ alloc5 (size: 8, align: 4) {`
	`59`	`++ alloc4 (size: 8, align: 4) {`
`60`	`60`	`+ 04 00 00 00 00 __ __ __ │ .....░░░`
`61`	`61`	`}`
`62`	`62`