Allow message printing with assert in the LLVM backend

src/libasr/codegen/asr_to_llvm.cpp

@@ -3150,8 +3150,15 @@ class ASRToLLVMVisitor : public ASR::BaseVisitor<ASRToLLVMVisitor>
         start_new_block(elseBB);
 
         {
-            llvm::Value *fmt_ptr = builder->CreateGlobalStringPtr("Assertion failed\n");
-            printf(context, *module, *builder, {fmt_ptr});
+            if (x.m_msg) {
+                char* s = ASR::down_cast<ASR::ConstantString_t>(x.m_msg)->m_s;
+                llvm::Value *fmt_ptr = builder->CreateGlobalStringPtr("AssertionError: %s\n");
+                llvm::Value *fmt_ptr2 = builder->CreateGlobalStringPtr(s);
+                printf(context, *module, *builder, {fmt_ptr, fmt_ptr2});
+            } else {
+                llvm::Value *fmt_ptr = builder->CreateGlobalStringPtr("AssertionError\n");
+                printf(context, *module, *builder, {fmt_ptr});
+            }
             int exit_code_int = 1;
             llvm::Value *exit_code = llvm::ConstantInt::get(context,
                     llvm::APInt(32, exit_code_int));

tests/reference/llvm-assert1-8df4f31.json

@@ -0,0 +1,13 @@
+{
+    "basename": "llvm-assert1-8df4f31",
+    "cmd": "lpython --no-color --show-llvm {infile} -o {outfile}",
+    "infile": "tests/assert1.py",
+    "infile_hash": "0ff84ea5ccd3d0815cbb66e1c3d3acd61dee7257c98aa1a27ceeef3b",
+    "outfile": null,
+    "outfile_hash": null,
+    "stdout": "llvm-assert1-8df4f31.stdout",
+    "stdout_hash": "43ba1e8f621d033901f9c161f1962b78a7861d5fc2abc225602f326c",
+    "stderr": null,
+    "stderr_hash": null,
+    "returncode": 0
+}

tests/reference/llvm-assert1-8df4f31.stdout

@@ -0,0 +1,51 @@
+; ModuleID = 'LFortran'
+source_filename = "LFortran"
+
+@0 = private unnamed_addr constant [20 x i8] c"AssertionError: %s\0A\00", align 1
+@1 = private unnamed_addr constant [11 x i8] c"a is not 5\00", align 1
+@2 = private unnamed_addr constant [16 x i8] c"AssertionError\0A\00", align 1
+
+define void @test_assert() {
+.entry:
+  %a = alloca i32, align 4
+  store i32 5, i32* %a, align 4
+  %0 = load i32, i32* %a, align 4
+  %1 = icmp eq i32 %0, 5
+  br i1 %1, label %then, label %else
+
+then:                                             ; preds = %.entry
+  br label %ifcont
+
+else:                                             ; preds = %.entry
+  call void (i8*, ...) @_lfortran_printf(i8* getelementptr inbounds ([20 x i8], [20 x i8]* @0, i32 0, i32 0), i8* getelementptr inbounds ([11 x i8], [11 x i8]* @1, i32 0, i32 0))
+  call void @exit(i32 1)
+  br label %ifcont
+
+ifcont:                                           ; preds = %else, %then
+  %2 = load i32, i32* %a, align 4
+  %3 = icmp ne i32 %2, 10
+  br i1 %3, label %then1, label %else2
+
+then1:                                            ; preds = %ifcont
+  br label %ifcont3
+
+else2:                                            ; preds = %ifcont
+  call void (i8*, ...) @_lfortran_printf(i8* getelementptr inbounds ([16 x i8], [16 x i8]* @2, i32 0, i32 0))
+  call void @exit(i32 1)
+  br label %ifcont3
+
+ifcont3:                                          ; preds = %else2, %then1
+  br label %return
+
+return:                                           ; preds = %ifcont3
+  ret void
+}
+
+declare void @_lfortran_printf(i8*, ...)
+
+declare void @exit(i32)
+
+define i32 @main() {
+.entry:
+  ret i32 0
+}

tests/tests.toml

@@ -148,6 +148,7 @@ filename = "assert1.py"
 ast = true
 asr = true
 cpp = true
+llvm = true
 
 [[test]]
 filename = "assign1.py"