Switch to the LLVMBuildGEPWithNoWrapFlags API

This API allows us to set the nuw flag as well.

compiler/rustc_codegen_llvm/src/builder.rs

@@ -32,7 +32,7 @@ use crate::abi::FnAbiLlvmExt;
 use crate::attributes;
 use crate::common::Funclet;
 use crate::context::{CodegenCx, SimpleCx};
-use crate::llvm::{self, AtomicOrdering, AtomicRmwBinOp, BasicBlock, False, Metadata, True};
+use crate::llvm::{self, AtomicOrdering, AtomicRmwBinOp, BasicBlock, False, GEPNoWrapFlags, Metadata, True};
 use crate::type_::Type;
 use crate::type_of::LayoutLlvmExt;
 use crate::value::Value;
@@ -908,13 +908,14 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
 
     fn gep(&mut self, ty: &'ll Type, ptr: &'ll Value, indices: &[&'ll Value]) -> &'ll Value {
         unsafe {
-            llvm::LLVMBuildGEP2(
+            llvm::LLVMBuildGEPWithNoWrapFlags(
                 self.llbuilder,
                 ty,
                 ptr,
                 indices.as_ptr(),
                 indices.len() as c_uint,
                 UNNAMED,
+                GEPNoWrapFlags::default(),
             )
         }
     }
@@ -926,13 +927,14 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         indices: &[&'ll Value],
     ) -> &'ll Value {
         unsafe {
-            llvm::LLVMBuildInBoundsGEP2(
+            llvm::LLVMBuildGEPWithNoWrapFlags(
                 self.llbuilder,
                 ty,
                 ptr,
                 indices.as_ptr(),
                 indices.len() as c_uint,
                 UNNAMED,
+                GEPNoWrapFlags::InBounds,
             )
         }
     }

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -954,6 +954,17 @@ bitflags! {
     }
 }
 
+// These values **must** match with LLVMGEPNoWrapFlags
+bitflags! {
+    #[repr(transparent)]
+    #[derive(Default)]
+    pub struct GEPNoWrapFlags : c_uint {
+        const InBounds = 1 << 0;
+        const NUSW = 1 << 1;
+        const NUW = 1 << 2;
+    }
+}
+
 unsafe extern "C" {
     pub type ModuleBuffer;
 }
@@ -1454,21 +1465,14 @@ unsafe extern "C" {
 
     pub(crate) fn LLVMBuildStore<'a>(B: &Builder<'a>, Val: &'a Value, Ptr: &'a Value) -> &'a Value;
 
-    pub(crate) fn LLVMBuildGEP2<'a>(
+    pub(crate) fn LLVMBuildGEPWithNoWrapFlags<'a>(
-        B: &Builder<'a>,
-        Ty: &'a Type,
-        Pointer: &'a Value,
-        Indices: *const &'a Value,
-        NumIndices: c_uint,
-        Name: *const c_char,
-    ) -> &'a Value;
-    pub(crate) fn LLVMBuildInBoundsGEP2<'a>(
         B: &Builder<'a>,
         Ty: &'a Type,
         Pointer: &'a Value,
         Indices: *const &'a Value,
         NumIndices: c_uint,
         Name: *const c_char,
+        Flags: GEPNoWrapFlags,
     ) -> &'a Value;
 
     // Casts

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -1767,6 +1767,24 @@ extern "C" LLVMValueRef LLVMRustBuildMaxNum(LLVMBuilderRef B, LLVMValueRef LHS,
   return wrap(unwrap(B)->CreateMaxNum(unwrap(LHS), unwrap(RHS)));
 }
 
+#if LLVM_VERSION_LT(19, 0)
+enum {
+  LLVMGEPFlagInBounds = (1 << 0),
+  LLVMGEPFlagNUSW = (1 << 1),
+  LLVMGEPFlagNUW = (1 << 2),
+};
+extern "C" LLVMValueRef
+LLVMBuildGEPWithNoWrapFlags(LLVMBuilderRef B, LLVMTypeRef Ty,
+                            LLVMValueRef Pointer, LLVMValueRef *Indices,
+                            unsigned NumIndices, const char *Name,
+                            unsigned NoWrapFlags) {
+  if (NoWrapFlags & LLVMGEPFlagInBounds)
+    return LLVMBuildInBoundsGEP2(B, Ty, Pointer, Indices, NumIndices, Name);
+  else
+    return LLVMBuildGEP2(B, Ty, Pointer, Indices, NumIndices, Name);
+}
+#endif
+
 // Transfers ownership of DiagnosticHandler unique_ptr to the caller.
 extern "C" DiagnosticHandler *
 LLVMRustContextGetDiagnosticHandler(LLVMContextRef C) {