coverage. MCDC ConditionId start from 0 to keep with llvm 19

Author: zhuyunxing

compiler/rustc_codegen_llvm/src/coverageinfo/ffi.rs

@@ -111,7 +111,7 @@ enum RegionKind {
 }
 
 mod mcdc {
-    use rustc_middle::mir::coverage::{ConditionInfo, DecisionInfo};
+    use rustc_middle::mir::coverage::{ConditionId, ConditionInfo, DecisionInfo};
 
     /// Must match the layout of `LLVMRustMCDCDecisionParameters`.
     #[repr(C)]
@@ -167,12 +167,13 @@ mod mcdc {
 
     impl From<ConditionInfo> for BranchParameters {
         fn from(value: ConditionInfo) -> Self {
+            let to_llvm_cond_id = |cond_id: Option<ConditionId>| {
+                cond_id.and_then(|id| LLVMConditionId::try_from(id.as_usize()).ok()).unwrap_or(-1)
+            };
+            let ConditionInfo { condition_id, true_next_id, false_next_id } = value;
             Self {
-                condition_id: value.condition_id.as_u32() as LLVMConditionId,
-                condition_ids: [
-                    value.false_next_id.as_u32() as LLVMConditionId,
-                    value.true_next_id.as_u32() as LLVMConditionId,
-                ],
+                condition_id: to_llvm_cond_id(Some(condition_id)),
+                condition_ids: [to_llvm_cond_id(false_next_id), to_llvm_cond_id(true_next_id)],
             }
         }
     }

compiler/rustc_middle/src/mir/coverage.rs

@@ -67,7 +67,7 @@ rustc_index::newtype_index! {
 }
 
 impl ConditionId {
-    pub const NONE: Self = Self::from_u32(0);
+    pub const START: Self = Self::from_usize(0);
 }
 
 /// Enum that can hold a constant zero value, the ID of an physical coverage
@@ -291,18 +291,8 @@ pub struct BranchSpan {
 #[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
 pub struct ConditionInfo {
     pub condition_id: ConditionId,
-    pub true_next_id: ConditionId,
-    pub false_next_id: ConditionId,
-}
-
-impl Default for ConditionInfo {
-    fn default() -> Self {
-        Self {
-            condition_id: ConditionId::NONE,
-            true_next_id: ConditionId::NONE,
-            false_next_id: ConditionId::NONE,
-        }
-    }
+    pub true_next_id: Option<ConditionId>,
+    pub false_next_id: Option<ConditionId>,
 }
 
 #[derive(Clone, Debug)]

compiler/rustc_mir_build/src/build/coverageinfo/mcdc.rs

@@ -106,22 +106,27 @@ impl MCDCState {
             }),
         };
 
-        let parent_condition = decision_ctx.decision_stack.pop_back().unwrap_or_default();
-        let lhs_id = if parent_condition.condition_id == ConditionId::NONE {
+        let parent_condition = decision_ctx.decision_stack.pop_back().unwrap_or_else(|| {
+            assert_eq!(
+                decision.num_conditions, 0,
+                "decision stack must be empty only for empty decision"
+            );
             decision.num_conditions += 1;
-            ConditionId::from(decision.num_conditions)
-        } else {
-            parent_condition.condition_id
-        };
+            ConditionInfo {
+                condition_id: ConditionId::START,
+                true_next_id: None,
+                false_next_id: None,
+            }
+        });
+        let lhs_id = parent_condition.condition_id;
 
-        decision.num_conditions += 1;
         let rhs_condition_id = ConditionId::from(decision.num_conditions);
-
+        decision.num_conditions += 1;
         let (lhs, rhs) = match op {
             LogicalOp::And => {
                 let lhs = ConditionInfo {
                     condition_id: lhs_id,
-                    true_next_id: rhs_condition_id,
+                    true_next_id: Some(rhs_condition_id),
                     false_next_id: parent_condition.false_next_id,
                 };
                 let rhs = ConditionInfo {
@@ -135,7 +140,7 @@ impl MCDCState {
                 let lhs = ConditionInfo {
                     condition_id: lhs_id,
                     true_next_id: parent_condition.true_next_id,
-                    false_next_id: rhs_condition_id,
+                    false_next_id: Some(rhs_condition_id),
                 };
                 let rhs = ConditionInfo {
                     condition_id: rhs_condition_id,
@@ -164,10 +169,10 @@ impl MCDCState {
         let Some(decision) = decision_ctx.processing_decision.as_mut() else {
             bug!("Processing decision should have been created before any conditions are taken");
         };
-        if condition_info.true_next_id == ConditionId::NONE {
+        if condition_info.true_next_id.is_none() {
             decision.end_markers.push(true_marker);
         }
-        if condition_info.false_next_id == ConditionId::NONE {
+        if condition_info.false_next_id.is_none() {
             decision.end_markers.push(false_marker);
         }