[clang] [CIR] Add if statement support (PR #134333)

[Bruno Cardoso Lopes via cfe-commits]

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@@ -442,6 +457,25 @@ class CIRGenFunction : public CIRGenTypeCache {
   mlir::LogicalResult emitDeclStmt(const clang::DeclStmt &s);
   LValue emitDeclRefLValue(const clang::DeclRefExpr *e);
 
+  /// Emit an if on a boolean condition to the specified blocks.
+  /// FIXME: Based on the condition, this might try to simplify the codegen of
+  /// the conditional based on the branch. TrueCount should be the number of
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bcardosolopes wrote:

This comment comes from OG, where the interface takes PGO information into account
```
  /// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an
  /// if statement) to the specified blocks.  Based on the condition, this might
  /// try to simplify the codegen of the conditional based on the branch.
  /// TrueCount should be the number of times we expect the condition to
  /// evaluate to true based on PGO data.
  void EmitBranchOnBoolExpr(const Expr *Cond, llvm::BasicBlock *TrueBlock,
                            llvm::BasicBlock *FalseBlock, uint64_t TrueCount,
                            Stmt::Likelihood LH = Stmt::LH_None,
                            const Expr *ConditionalOp = nullptr);
```

https://github.com/llvm/llvm-project/pull/134333