rustc_trans: do not pass floating-point values to LLVM through FFI.

Author: eddyb

src/librustc_llvm/ffi.rs

@@ -598,7 +598,6 @@ extern "C" {
     // Operations on scalar constants
     pub fn LLVMConstInt(IntTy: TypeRef, N: c_ulonglong, SignExtend: Bool) -> ValueRef;
     pub fn LLVMConstIntOfArbitraryPrecision(IntTy: TypeRef, Wn: c_uint, Ws: *const u64) -> ValueRef;
-    pub fn LLVMConstReal(RealTy: TypeRef, N: f64) -> ValueRef;
     pub fn LLVMConstIntGetZExtValue(ConstantVal: ValueRef) -> c_ulonglong;
     pub fn LLVMConstIntGetSExtValue(ConstantVal: ValueRef) -> c_longlong;
     pub fn LLVMRustConstInt128Get(ConstantVal: ValueRef, SExt: bool,

src/librustc_trans/base.rs

@@ -832,8 +832,7 @@ fn create_imps(sess: &Session,
                 let imp = llvm::LLVMAddGlobal(ll.llmod,
                                               i8p_ty.to_ref(),
                                               imp_name.as_ptr() as *const _);
-                let init = llvm::LLVMConstBitCast(val, i8p_ty.to_ref());
-                llvm::LLVMSetInitializer(imp, init);
+                llvm::LLVMSetInitializer(imp, consts::ptrcast(val, i8p_ty));
                 llvm::LLVMRustSetLinkage(imp, llvm::Linkage::ExternalLinkage);
             }
         }

src/librustc_trans/common.rs

@@ -223,12 +223,6 @@ pub fn C_big_integral(t: Type, u: u128) -> ValueRef {
     }
 }
 
-pub fn C_floating_f64(f: f64, t: Type) -> ValueRef {
-    unsafe {
-        llvm::LLVMConstReal(t.to_ref(), f)
-    }
-}
-
 pub fn C_nil(ccx: &CrateContext) -> ValueRef {
     C_struct(ccx, &[], false)
 }

src/librustc_trans/consts.rs

@@ -36,6 +36,12 @@ pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef {
     }
 }
 
+pub fn bitcast(val: ValueRef, ty: Type) -> ValueRef {
+    unsafe {
+        llvm::LLVMConstBitCast(val, ty.to_ref())
+    }
+}
+
 pub fn addr_of_mut(ccx: &CrateContext,
                    cv: ValueRef,
                    align: machine::llalign,

src/librustc_trans/mir/constant.rs

@@ -27,7 +27,7 @@ use abi::{self, Abi};
 use callee;
 use builder::Builder;
 use common::{self, CrateContext, const_get_elt, val_ty};
-use common::{C_array, C_bool, C_bytes, C_floating_f64, C_integral, C_big_integral};
+use common::{C_array, C_bool, C_bytes, C_integral, C_big_integral};
 use common::{C_null, C_struct, C_str_slice, C_undef, C_uint, C_vector, is_undef};
 use common::const_to_opt_u128;
 use consts;
@@ -96,11 +96,11 @@ impl<'tcx> Const<'tcx> {
         let llty = type_of::type_of(ccx, ty);
         let val = match cv {
             ConstVal::Float(v) => {
-                let v_f64 = match v {
-                    ConstFloat::F32(v) => f32::from_bits(v) as f64,
-                    ConstFloat::F64(v) => f64::from_bits(v)
+                let bits = match v {
+                    ConstFloat::F32(v) => U32(v),
+                    ConstFloat::F64(v) => U64(v)
                 };
-                C_floating_f64(v_f64, llty)
+                consts::bitcast(Const::from_constint(ccx, &bits).llval, llty)
             }
             ConstVal::Bool(v) => C_bool(ccx, v),
             ConstVal::Integral(ref i) => return Const::from_constint(ccx, i),