Rollup merge of #101612 - tmiasko:repeat128, r=lcnr

Fix code generation of `Rvalue::Repeat` with 128 bit values

Closes #101585.

Author: Dylan-DPC

compiler/rustc_codegen_llvm/src/common.rs

@@ -215,7 +215,11 @@ impl<'ll, 'tcx> ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
     }
 
     fn const_to_opt_uint(&self, v: &'ll Value) -> Option<u64> {
-        try_as_const_integral(v).map(|v| unsafe { llvm::LLVMConstIntGetZExtValue(v) })
+        try_as_const_integral(v).and_then(|v| unsafe {
+            let mut i = 0u64;
+            let success = llvm::LLVMRustConstIntGetZExtValue(v, &mut i);
+            success.then_some(i)
+        })
     }
 
     fn const_to_opt_u128(&self, v: &'ll Value, sign_ext: bool) -> Option<u128> {

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -1096,7 +1096,7 @@ extern "C" {
     pub fn LLVMConstInt(IntTy: &Type, N: c_ulonglong, SignExtend: Bool) -> &Value;
     pub fn LLVMConstIntOfArbitraryPrecision(IntTy: &Type, Wn: c_uint, Ws: *const u64) -> &Value;
     pub fn LLVMConstReal(RealTy: &Type, N: f64) -> &Value;
-    pub fn LLVMConstIntGetZExtValue(ConstantVal: &ConstantInt) -> c_ulonglong;
+    pub fn LLVMRustConstIntGetZExtValue(ConstantVal: &ConstantInt, Value: &mut u64) -> bool;
     pub fn LLVMRustConstInt128Get(
         ConstantVal: &ConstantInt,
         SExt: bool,

compiler/rustc_codegen_ssa/src/mir/rvalue.rs

@@ -87,7 +87,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     let size = bx.const_usize(dest.layout.size.bytes());
 
                     // Use llvm.memset.p0i8.* to initialize all zero arrays
-                    if bx.cx().const_to_opt_uint(v) == Some(0) {
+                    if bx.cx().const_to_opt_u128(v, false) == Some(0) {
                         let fill = bx.cx().const_u8(0);
                         bx.memset(start, fill, size, dest.align, MemFlags::empty());
                         return bx;

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -1618,6 +1618,14 @@ extern "C" LLVMValueRef LLVMRustConstInBoundsGEP2(LLVMTypeRef Ty,
   return wrap(ConstantExpr::getInBoundsGetElementPtr(unwrap(Ty), Val, IdxList));
 }
 
+extern "C" bool LLVMRustConstIntGetZExtValue(LLVMValueRef CV, uint64_t *value) {
+    auto C = unwrap<llvm::ConstantInt>(CV);
+    if (C->getBitWidth() > 64)
+      return false;
+    *value = C->getZExtValue();
+    return true;
+}
+
 // Returns true if both high and low were successfully set. Fails in case constant wasn’t any of
 // the common sizes (1, 8, 16, 32, 64, 128 bits)
 extern "C" bool LLVMRustConstInt128Get(LLVMValueRef CV, bool sext, uint64_t *high, uint64_t *low)

src/test/ui/codegen/issue-101585-128bit-repeat.rs

@@ -0,0 +1,14 @@
+// Regression test for issue 101585.
+// run-pass
+
+fn main() {
+    fn min_array_ok() -> [i128; 1] {
+        [i128::MIN]
+    }
+    assert_eq!(min_array_ok(), [-170141183460469231731687303715884105728i128]);
+
+    fn min_array_nok() -> [i128; 1] {
+        [i128::MIN; 1]
+    }
+    assert_eq!(min_array_nok(), [-170141183460469231731687303715884105728i128]);
+}