Emit getelementptr nuw for IndexExp in static array with const exp

Author: kubo39

gen/toir.cpp

@@ -1198,7 +1198,16 @@ class ToElemVisitor : public Visitor {
       }
       LLType *elt = DtoMemType(e1type->nextOf());
       LLType *arrty = llvm::ArrayType::get(elt, e1type->isTypeSArray()->dim->isIntegerExp()->getInteger());
-      arrptr = DtoGEP(arrty, DtoLVal(l), DtoConstUint(0), DtoRVal(r));
+#if LDC_LLVM_VER >= 2000
+      llvm::GEPNoWrapFlags nw = llvm::GEPNoWrapFlags::inBounds();
+      if (e->indexIsInBounds)
+        nw |= llvm::GEPNoWrapFlags::noUnsignedWrap();
+#endif
+      arrptr = DtoGEP(arrty, DtoLVal(l), DtoConstUint(0), DtoRVal(r)
+#if LDC_LLVM_VER >= 2000
+                    , "", nullptr, nw
+#endif
+      );
     } else if (e1type->ty == TY::Tarray) {
       if (p->emitArrayBoundsChecks() && !e->indexIsInBounds) {
         DtoIndexBoundsCheck(e->loc, l, r);

gen/tollvm.cpp

@@ -428,10 +428,19 @@ LLValue *DtoGEP(LLType *pointeeTy, LLValue *ptr, unsigned i0, unsigned i1,
 }
 
 LLConstant *DtoGEP(LLType *pointeeTy, LLConstant *ptr, unsigned i0,
-                   unsigned i1) {
+                   unsigned i1
+#if LDC_LLVM_VER >= 2000
+                 , llvm::GEPNoWrapFlags nw
+#endif
+                  ) {
   LLValue *indices[] = {DtoConstUint(i0), DtoConstUint(i1)};
   return llvm::ConstantExpr::getGetElementPtr(pointeeTy, ptr, indices,
-                                              /* InBounds = */ true);
+#if LDC_LLVM_VER >= 2000
+                                              nw
+#else
+                                              /* InBounds = */ true
+#endif
+                                            );
 }
 
 LLValue *DtoGEP1i64(LLType *pointeeTy, LLValue *ptr, uint64_t i0, const char *name,

gen/tollvm.h

@@ -102,7 +102,11 @@ LLValue *DtoGEP(LLType *pointeeTy, LLValue *ptr, unsigned i0, unsigned i1,
 #endif
               );
 LLConstant *DtoGEP(LLType *pointeeTy, LLConstant *ptr, unsigned i0,
-                   unsigned i1);
+                   unsigned i1
+#if LDC_LLVM_VER >= 2000
+                 , llvm::GEPNoWrapFlags nw = llvm::GEPNoWrapFlags::inBounds()
+#endif
+                  );
 
 LLValue *DtoGEP1i64(LLType *pointeeTy, LLValue *ptr, uint64_t i0,
                     const char *name = "", llvm::BasicBlock *bb = nullptr

tests/codegen/inbounds.d

@@ -9,7 +9,7 @@ extern(C):  // Avoid name mangling
 // IndexExp in static array with const exp
 // CHECK-LABEL: @foo1
 int foo1(int[3] a) {
-    // CHECK: getelementptr inbounds [3 x i32]
+    // CHECK: getelementptr inbounds{{( nuw)?}} [3 x i32]
     return a[1];
 }